Stalling when stopped or driving slow sometimes?....

Asked by Aug 30, 2015 at 03:34 AM about the 1991 Lincoln Mark VII LSC

Question type: Maintenance & Repair

I have a 1991 Lincoln LSC  Mark seven and
recently when I am driving it and I come to a
stop sign or red light my idol will fluctuate
between 500 and  1000 RPMs.  If I do not
push the gas when this happens it will Stall.  
Sometimes it may also have purges of power
as if I was pushing the gas when I'm not.  
The strange thing is it is not consistent one
day could happen and the next day I could
drive the car without a problem.  I tried
replacing the idle control valve but no use.  
There is no check engine light on.

9 Answers


its funny I had a lincoln lsc 5.0 HO mark 7 and this is a common problem what I would point at first is the Idle Air control motor and believe me this is more then likely the problem. I have added a picture of what it looks like for you to find it. you can clean it out the get filled with carbon but new is always good. try cleaning it out first and see what happens. you can see it in the picture its the thing that looks new. what it does is adjusts the air flow through to give it proper idle and if it has carbn or not working right it cant find the proper placement and there for the raising and lowering of the idle it does.

Best Answer Mark helpful

Check air filter and clean throttle body replace fuel filter add Lucas Fuel Injector Cleaner to gas tank.

I replaced the idle control valve which is the part In the picture shown and I took it to a shop and they think it is my (exhaust gas recirculator).... I tried adding fuel injector cleaner to my tank and it seemed to run better at least until I filled up my tank again .... Octane boost did nothing and fuel system cleaner did nothing. Fairly new air filter. I think I had three or four of my eight fuel injectors replaced three or so years ago but I was told if my fuel injectors were the problem it would be more consistent... I appreciate all the help.


it could be a vacuum leak to. just like the IAC valve it allows a certain amount of air in to mix with the gas to make it run right. if there is a vacuum leak it could be that the computer is trying to find through the IAC the proper idle. this is a easy check and I'm sorry I didn't have you try this before but get a can of carb clean and spray it around the intake and over the vacuum lines. if the idel straightens out when doing this look at the area that you are spraying.

I tried that already didn't hear a leak and the idol did not pick up.. When I sprayed my hoses. Something like this happened a few years ago and strangely enough it seems like changing my cars computer fixed the problem but how could that go bad again in three or four years.... That's extremely rare. The car only has 80,000 miles on it but like 10 years ago there was some water damage due to leaking sunroof ( which is now fixed ) so most of the electronics were changed but I have a feeling it might be electrical...... Sometimes I get purges of power as if I was pushing the gas But I'm not sure if this is all linked together or not


You may want to google this to check out the symptoms that it causes when this part goes bad sounds a lot like your symptoms you are having ( Toque Converter Clutch Solinoid ). Not saying this is your problem but it is one you need to look into.


And also since you said it seemed to run a little better after adding fuel injector cleaner to gas tank do a sea foam spray cleaner and lube.

Thanks so much. Another thing is it seams to drive better at night weather that means it drives better when it's cooler or when there is less traffic i dont know ?

Just an update I replaced the EGR valve also... It did have some carbon buildup but I am still having the problems. I am so lost now .

Your Answer

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