Taking it to an expert is a lot less expensive than throwing a bunch of parts at it. Now that you've changed a lot of things and made adjustments, there are a whole lot of new variables. None of the parts listed will cause a problem only in park. You will never solve a low-speed running problem on a Chrysler product by replacing the fuel filter.
When sensors are replaced, the engine will not run well until the engine computer updates to learn the new values. As an example, no two coolant temperature sensors will read the same resistance at a given temperature. The computer compares it to the ambient air temp. Sensor after the engine has been off for a specified period of time. With a new sensor, a different-than-expected reading will confuse the computer. With a known incorrect sensor reading, the computer will inject a pre-programmed value if it doesn't trust the current reading, and run off of that. It won't run well, but it's better than no sensor reading at all. With the original intermittent problem AND confusing sensor values, the engine might not run properly even if you accidentally fix the original problem.
The most effective way to fix this type of problem is to diagnose the cause and repair only that. If you are going to just try replacing parts, you should only replace one at a time, then, if it doesn't solve the problem, put the original part back in.
There were some problems with worn bushings in the distributor. That will cause erratic ignition timing but it won't clear up in park. You might try flexing wiring harnesses that move as the engine moves when placed in gear. Corroded connector pins are another source of problems that act up when the engine moves.
Wednesday, May 20th, 2009 AT 2:33 AM