Different problems when accelerating

[Th3DooM]

Okay, you helped me alot in the past months, but I have different problems when accelerating with my 98GS.
When I hit the gas it seems that the engine moves backwards. I guess my motor mounts are worn so I wanna get some urethan mounts but don't know if I need new stock mounts (the urethans are just inserts, right?). I'd like to replace as much rubber as possible with urethan.

Then I often have the problem that my car accelerates really slow. Not like "it's no turbo, why do you wonder"-slow, just real damn slow like I lost about half its power. In the other moment the car runs great, accelerates smooth and faster than before.

When my rpm is about 1700 to 2000 and I try to hold the speed, the car starts to shake like pushing the gas and release it really fast mixed with the feeling of driving on a gravel track. The Accelerator is pushed just a little. Could a dirty throttle body or intake manifold/idle control cause this?

These problems exist since I own my car. I had trouble with the ignition system and changed the spark plugs, wires and coil about 2 months ago. At least I got rid of the randomly jumping rpms. I hope you can help me.

Btw I would be happy if you could help me with my suspension problem as well:

http://www.dsmtuners.com/forums/handling-tech/432936-megan-racing-ez-series-good-dd.html

 

[Fotowntalon]

Did you check for a clogged cat?

 

[Th3DooM]

Is it possible to check the cat without removing the exhaust piping?

Some weeks ago my cel threw a code for the o2 sensor but it went off by itself. Also a mechanic told me it sounds like there is no cat on my car anymore but I guess it's just a little rust hole at the end of the piping...

Edit: how could it be that the cat unclogs itself? Could the exhaust gas stasis cause overheating in idle?

 

[Fotowntalon]

To check it, let it warm up then look under the car, the cat will be glowing bright orange. And I could see it causing overheating, I mean hot gas pressure has very little escape route, causing a back up making the headers hotter, making the head hotter and etc. Well makes sense in my head.

 

[Th3DooM]

No glowing cat in the dark. A friend told me a faulty camshaft sensor could cause similar problems. what do you think?

 

[Th3DooM]

Sorry for bumping my own thread!

A little update:
Long story:
On saturday (April 14th) I had to disconnect my battery due to recharging. After the battery was charged I installed it back into the engine bay and started the car. I let it idle for about 5 -10 minutes and then turned it off.

This week the car drives much better and accelerates like a totally other car. But I have a new problem: When I engage the clutch the rpm will stay at the range I drove. It even won't calm down after 5 seconds, so I have to push the gas pedal a bit and after that the idle falls to about 900-1000rpm (before I disconnected the battery idle stayed at about 800-900).

tl;dr-version:

disconnected battery, car runs much better, but after engaging clutch idle stays at 2000rpm. have to push gas pedal for normal idle. Where to look at?

 

[BoostedPhoenix]

Throttle position sensor is a common failure item on these engines that will cause idle and driveability problems, it also takes some time for the computer to diagnose itself of this problem. Without a CEL or a computer to check values its just a guessing game. Good luck.