Negative timing!!!!! Sputter!!! WTF

[pickens]

I'm really frustrated now and I'm actually ready to take my car to the dealer to have it fixed or sell it! I need some ideas here people...Recently my car has been sputtering under wot from 3k-5krpm. It usually starts around when full boost hits(15psi). After 5k it straightens up and runs til redline. So here's what Ive done so far to fix it........
Spark plugs and wires (changed)
Coil packs (changed)
ICM (power transistor) (changed)
fuel filter (changed)
fuel pump (changed)
injector cleaner
MAF (changed)
checked timing belt marks on cams


I've also did a boost leak test. This may or may not be my problem. I could only get 5psi when I tested the manifold portion. I sprayed soapy water everywhere and fixed a couple of small leaks but, still only 5psi. I can't find or hear any other leaks, but something is not right with only 5psi? My idle vaccumm usually sit around 16 mm mg as well. Sometimes it sit around 18 but mostly 16. Also, the car is now doing it even under medium acceleration (75% throttle). It doesnt do it all the time either, more so in second gear, hardly ever in first gear, and seldomly in third. So I decided to log in 2nd gear and see if i could see what happens. Well, from about 3700rpm til 5000rpm the car studdered and bucked hard. The log showed timing was NEGATIVE -3! and 0 degrees while the bucking was happening!!!! My O2's were around .98-.96. I did notice my blinky a/f gauge moved a light every time it missed or studdered. I'm thinking this is some sort of electrical problem since it doesn't happen all the time, rather than being a boost leak related problem. Some days, the car absolutely screams! then other days it just studders and bucks. I also thought it was maybe fuel cut since I was running about17-18psi, but then I turned it down to 14-15psi and the car ran perfect......for about a week, and then the same problem and its not getting any better. So, I guess I explained all that I can.....HELP!

 

[splattj]

Have your alternator tested. If it isn't putting out enough juice the car will sputter. It could be that by 5k RPMs the output has been forced high enough by spinning the alternator fast.

 

[pickens]

I forgot to mention, I put in a brand new battery as well. But maybe the alternator although I doubt it because usually the battery drains when the alternator dies, also it doesn't eaxctly do it everytime.

 

[splattj]

I had a similar problem. The car always started, seemed to run fine. Didn't get any lights in the dash but it turns out the the alternator was only working intermittently. It would be putting out 11v below ~2500 RPM and would jump up to 13+ above 5k. It took me three months before it got bad enough that I stopped where it happened and jumped out of the car with a multimeter. Just get the thing tested for free.

 

[pickens]

I still don't think thats the problem because when you drain alot of energy at once it usually comes from the battery, and the alternator just recharges it. But, I'll check it anyway. I'll try anything at this point! I might even get talked into changing my muffler bearings.