Once the fuel pump is running on a Chrysler product, it is extremely rare for them to cause a problem while driving. By just throwing more and more parts at it, you're adding more variables and potential problems. This will make it very hard to diagnose the original problem.
It is almost unheard of to fix a running problem on a Chrysler product by replacing the fuel filter. It is more likely you'll find a plugged pickup screen in the tank, but the symptom will be the engine dies when the largest volume of fuel is being pumped, which is during coasting at highway speeds. Less fuel is moved during acceleration so it's easier to maintain the necessary pressure.
The "rings" for the spark plugs are gaskets. Although unlikely, pull a spark plug back out and check the gap. Without the gasket in place, the plug could have been screwed in too far, and the piston might have hit the electrode closing the gap. Since the no-start problem first occurred after replacing the plugs, wouldn't it make sense to put the old plugs back in? At the very least, physically compare a new plug to an old one.
As for sluggish running, my first guess would be a MAP sensor, particularly since throttle position had an effect on the symptom. Now that it doesn't start at all, I would suspect a defective camshaft position sensor or crankshaft position sensor. Normally, either of these sensors will set a diagnostic fault code and turn on the "Check Engine" light. Retrieving the fault code will tell you which sensor is causing the problem. It is possible for the MAP sensor to report incorrect values that result in poor performance, but as long as the incorrect values fall within the acceptable range, a fault code will not be set in memory. Eventually, the sensor will fail completely; then a fault code will be set, and the Check Engine light will turn on.
Wednesday, May 27th, 2009 AT 5:05 PM