91 Stealth TT. Need help with misfiring or other problem.

I just bought a 91 stealth r/t twin turbo. It is in great shape with a little over 80k miles. But when I'm driving it, it lunges forward and backward badly. It's worse above 3K rpm. If I floor it though, it seems to run fine. However, if you are behind the car when it gets floored, it shoots a quick puff of black smoke and in high rpm when I let off the throttle to shift, it backfires sometimes.

I am trying to decide if I should replace the plugs, or the coil packs, or the plug wires. Then I figured it might be the PTU. Any idea on what could be happening. It is very bad. It will spill a drink in the couple holder just because it jumps so hard.

Your help would be greatly appreciated by this new Stealth owner.

thanks,
Justin

do you have a blow off valve? an after market one i mean

No, it has the stock BOV's, or recircs, not sure which is stock.

hmm.. that's what i was wondering.. if it is recirculates..
not sure.. but if you do start replacing parts.. I can get you factory parts 25% off..

I am trying to decide if I should replace the plugs, or the coil packs, or the plug wires. Then I figured it might be the PTU. Any idea on what could be happening. It is very bad. It will spill a drink in the couple holder just because it jumps so hard.

how bout all of the above. you just bought the car so best thing to do is to get a full tune up..make sure to change your timing belt and water pump while your at it


Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

how bout all of the above. you just bought the car so best thing to do is to get a full tune up..make sure to change your timing belt and water pump while your at it


Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.
It does smell like fuel. And gas mileage is terrible. I dunno about the performance, this is my first one but it seems pretty fast, but probably not as fast as it should. I read something earlier about something leaking in the ECU. Could this be my problem?