I've recently had a lot of work done to my car. The balance shaft chain, and timing belt were all replaced (along with the miriad of other nickel and dime parts that go with them).

Before that, I replaced the crank position and cam posistion sensors to fix a stalling issue. While I was at it, I noticed the spark plug tops drenched in oil, so i replaced the valve cover gasket, plugs and wires. This seemed to fix most of my issues. At least the car stays running.

However, I still have an shaking steering wheel and brake pedal when idling at 750rpm. Also, the check engine light flashes a few times after long stretches of highway driving (about 30 minutes). The wierd part is that it doesn't stay on! I think it indicates misfire.

Other clues: The engine idles fairly smooth in park and neutral, it gets rough when the tranmission is engaged. I notice that when I'm slowing down (and the engine is shifting from 2nd to 1st gear), the RPM's dip momentarily, like the car is stumbling then it recovers.

I'm thinking that these two issues might be connected by a vacuum leak?

Is there any thing else that could cause this behavior?

PCV valve is good. EGR?

 

Any luck with fixing this issue? I have the same problem with my 99 2.5L