Have you searched the topic..... I swear every week there is always a new thread, about the same issue. Non of them seem to ever get solved, in currently chasing the same ghost as you, in fact there are a handful of people waiting for you or me to find a solution so they can resolved their issue.....
There is alot, I mean alot of variables that can be the cause. Pretty much every component of fuel, air and spark. Start testing everything. Good luck.

Yes I have searched the forums. I have tested everything up to the cas and so far all seem to be working fine tps is set to .51 volts. I just don't understand how it could happen only under load especially bouncing like a Rev limiter when I don't have one

I'm as lost as you. i just recently installed a new alternator as a "hail Mary" hoping it would work..........no changed.
i have an active thread, feel free to review it and see if any of the procedures i carried out can help you. One of those things i did may help you even if they didn't work for me, Also i don't know why their isn't a mega thread on this the same way there is for overheating and all the other subjects out there.

I think it could be something in the electronic components themselves, or just the software. I think.

Wot Does the car speed up and the then feel like it loses and speeds up again? feels like the car is wanting to buck forward and backward as your moving?

Did you try disconnecting your wastegate mechanically? I have seen wastegates flutter as they get old and cause this kind of problem. Only way to know for sure is to disconnect the linkage and then tie the gate shut and take it on a careful test drive.

Do you have a wideband to view those afrs? Can you verify that the keydriver settings are correct? The 2g maf flows 33% more than than the 1g maf does. Also I'm unsure about manually setting the tps volts but with link it should be .63v not .51v.

If you have link and 2-step is at 3500 and the ECU isn't getting a speed signal, then you will have this problem because the ECU will think the car isn't moving. Log and see if you are getting a speed reading.

90_AWD_Thunder said:

I am currently running a key driver chip set up for 450cc and a 2g Mas

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Can you post a picture of the ECU including the KeyDiver chip.

Type1DSMr said:

Also I'm unsure about manually setting the tps volts but with link it should be .63v not .51v.

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The factory spec for the TPS output voltage on a 1G is 0.50v +- 0.02v at curb idle. The KeyDiver chip doesn't change any code that would effect this. (As an aside, DSMLink is quite happy to function with a TPS adjusted to factory specs)

Ok check continuity on the tps today and pins 1 and 4 tested at 4.3k ohms and when checking the throttle response it went from 4.3k (in spec) to "out of limit" on my multi meter and yes Steve I will post a pic gimme a day or two business is getting crazy here

Alright replaced tps today again starts up and runs fine but still the cut out at 3500 happens. CEL came on now and can't get any communication to the ecu with scan tool or using a jumper wire.

Maybe you already checked it but I had a similar problem to what nick97 said. Car would buck all over the place and wouldn't do anything after about 3700 or so in any gear. I checked the timing and it had worked its way off. Dialed it back to 10deg btdc and solved it. Not sure if cps nuts were not torqued correctly or what but it wasn't where it was supposed to be.

Have also seen clogged cats do similar craziness. But I'm guessing this happened after tbelt change?

crash said:

Maybe you already checked it but I had a similar problem to what nick97 said. Car would buck all over the place and wouldn't do anything after about 3700 or so in any gear. I checked the timing and it had worked its way off. Dialed it back to 10deg btdc and solved it. Not sure if cps nuts were not torqued correctly or what but it wasn't where it was supposed to be.

Have also seen clogged cats do similar craziness. But I'm guessing this happened after tbelt change?

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It's supposed to be 5* BTDC with the timing pin grounded and 8* BTDC without. Both are at idle.

whoops. thanks, Chump. it's also helpful to have someone else check your work.

either way, a little advanced is good. too much advance equals spark knock, wild mustang bucking bronco driving...may not be your problem but it's easy to check.

just wondering what type of boost controller are you using?

I am running a Hallman pro boost controller

Nick97dsm said:

just wondering what type of boost controller are you using?

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And this leads you to conclude what diagnosis?

While many have good intentions, I can't help but feel as many responses as questions, that are not really contributing to the op, but only to the post count of those who ask.

Op. I have done more reading, and outside the expected reading for causes, I have stumbled on other sites for other boosted cars. Some unorthodox solutions have been checking the vac on the BOV with same tool used to bleed brakes.
And popping vc of to check for rockers, in case one feel... Also dealing with this, I went to high yard and picked up ignition parts from a 2g spyder, will try those. Reason is while ignition parts can read in spec while testing they may fail under load..
I'll attempt to share more, outside the box diagnosis and attempts with you. Rather then asking you pointless questions.

I had this happen to me on an 89 Colt gt that I did a 4g63t swap on. It ended up being the MASS airflow sensor.

Well consider this resolved I switched ecu back to a stock ecu with a 2g Mas and 560s and she revs to no end now she runs lean of course but storing for the winter and link is on the way thanks for all the input and best of luck Miliman if I can think of anything else I will send a post to you

Depending on how the code in that KeyDiver chip was written the fact that you have an auto car, where ECU pin 104 is used for the Park/Neutral switch may be confusing the launch limiter code.
It's also possible that you have a bad VSS reed switch in your speedometer so that the ECU isn't seeing that the car is moving. Both of these are often used as inputs to the logic for a stutterbox.

the questions i ask are to try to figure out if the part can be a problem like for instants i have had multiple aem tru-boost parts fail and give me problems with rev limiting so don't shoot down simple questions that others ask when trying to help makes you sound like an ignorant a$$ so take it as you will.