Expert: Skip Bollinger - 7/12/2007

Question
hi i have a 1995 lincoln town car ,it cuts it start to cut off when i am driving but not when its idling ,i have donne complet tune up ,replaced the EGR valve to,and still doing same thing i was told buy the dealer it could be a vacum probleme ,i couldnt find the vacum diagram, i hope you cant tell me what is the probleme.
thank you and god bless.
joseph

Answer
Joseph,
  Your inquiry raises more questions for me to ask you. Please look at my Profile, I'm a Parts Professional, NOT a tech but will do my best to assist you. Here are questions I have for you..
1.  What did you replace in the "complete tune up"?
2.  Did this begin all of a sudden or has it been a gradually increasing problem?   
3.  If it is in Park and you try to rev up the engine, will it rev up or does it stall?
4.  Have you checked the fuel pressure while driving?
5.  Have you checked the exhaust flow?
6.  When it begins to stall, does the exhaust blow black smoke?
  I don't think it is a vacuum problem since that would cause a high idle and the engine would want to die when you put it in gear.
  My thoughts lead in 3 directions:
1. A partially plugged filter causing a loss of air OR
2. Fuel at a moderate RPM (35 mph).
  The air filter could be plugged up OR the fuel filter on the fuel pump, in the gas tank (called the Sock) could be picking up debris.
3.  The last thought is a plugged exhaust. Breathe heavily out of your nose. Now, with your finger, close one nostril and try to breathe heavily. See how things just don't move as easily? That could be the same way with the exhaust. It is called back pressure. Engines don't like this much back pressure.
  Again, I don't think it is a vacuum problem but you can get a vacuum diagram at your local Public Library. They have a section called a "Reference Section". You can't check out the books but you can photocopy them and take that home to look at.
  Joseph, if you have the resources to check the above suggestions, I think you will find your problem. IF you don't, get back with me and we can take this one step at a time. Good luck and thank you for your question.
Skip