i have a 5.0 liter engine in a 88 lincoln town car . some times when i start the car and its idiling the rpms jump all over but the engine does not rev up or stall. and when i drive it stumbels when the engine is under load but ounce up to cruise it seems fine .but if the rpms start to jump it will stumbel. could this be the tfi ignition modual and if so how do i check it and replace. any help would be appreciated.

 

it sounds like it may be an egr problem, the egr is only ment to come on durring cruise, and it it is stuck a little open, it will choke the car and make it do what you are talking about. check the vacume line going to it, it may be leaking, or have no vaccum at all.

 

really sounds like a vacum leak problem. Check all visible vaum lines for cracking and replace as necessary.