My 2000 GTP @ 140K miles is running horrible only while idling and shakes my whole car. As soon as I hit the gas the engine seems to accelerate perfectly smooth with no roughness at all.

Mechanic told me it's definitly misfiring. 3 different mechanics including 1 dealership have looked at it and can't figure out what the cause of the problem is without tearing the engine apart.

One person suggests a valve job, another suggests bad fuel pump or injectors, another suggests replacing the engine! gulp

Any thoughts? I love this car and would hate to get rid of it.