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Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Mercury Technician
Category: Mercury
Satisfied Customers: 43862
Experience:  16 years experience with Mercury
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2000 mercury cougar, car used to idle rough, shake and sometimes

Customer Question

2000 mercury cougar, car used to idle rough, shake and sometimes die when i stopped. Now when i start it, it revs up and then dies.
Submitted: 6 years ago.
Category: Mercury
Expert:  Chris (aka- Moose) replied 6 years ago.

Hello Zacmac


I'm Chris, Thanks for allowing me to help you here on Just Answer.


So far you have described a faulty idle air control valve which controls the engine idle rpm. It is mounted o nthe throttle body on the top of the engine. I recommend you start by replaceing it.

Customer: replied 6 years ago.
How come it messed up and then it was fine for 2 months with no problems and now its worse?
Expert:  Chris (aka- Moose) replied 6 years ago.
The IAC valve is what it is, its a valve. It allows air to pass by it and keep the engine running at the correct rpm whether at idle or while under a load from the AC or alternator or while in gear in traffic. This valve sometimes gets stuck and or gums up and cant move well. Odds are it got stuck then was able to move again and now its gotten stuck again in a worse positon.
Chris (aka- Moose) and 2 other Mercury Specialists are ready to help you
Customer: replied 6 years ago.
did as you said and replaced the IAC valve and im still having the same problem, it starts up revs really high and then idles down and dies.
Expert:  Chris (aka- Moose) replied 6 years ago.

Did you reset the PCM by removing the negative battery cable for 5 minutes. if not try this then get back with me.

Also check for vacuum hose or PCV hose leaks.

Customer: replied 6 years ago.
No leaks that I can see and don't really have time to listen for soon as I start it it revs up then dies. The times I have had this problem is when it was really cold and I had below a 1/4 tank of gas. There is a recall on the fuel filter. Could that be it?
Expert:  Chris (aka- Moose) replied 6 years ago.
The only way it could be a fuel filter concern is if you have never serviced it or the fuel pressure is low.
Customer: replied 6 years ago.
I replaced the fuel filter, the filter was rusted and the fuel that drained out of it was brown. The car does not rev up and die anymore. now it starts and just idles rough and sometimes dies. I feel dumb but i couldn't find the PCV on the engine. Could you tell me where its located. It only messes up when its cold, could it be the air charge temperature sensor. I forgot to mention something that now I feel might be important. A while back a guy at a new gas station said my car could use E30 and i used it for almost 2 months, when my car messed up the first time i started using regular gas and i put the heet and fuel injector cleaner in. I am sure the e30 has flushed out by now but could it of done some damage?
Expert:  Chris (aka- Moose) replied 6 years ago.
E30 is a no no in this vehicle. Its not a flex fuel vehicle. Ethanol attracts water and causes rust this is why all flex fuel vehicles use everything stainless steel with touches fuel. That rust you found i n the filter is not good. Your most likely looking at some rusted up fuel lines which have also clogged up the fuel injectors somewhat meaning the lines and injectors and pump needs to be replaced.
Customer: replied 6 years ago.
so what do you think my best next step would be? Pay $90 to have ford diagnos it? or start replacing stuff?
Expert:  Chris (aka- Moose) replied 6 years ago.
Removering the injectors and inspecting them and flow testing them are the next steps.
Customer: replied 6 years ago.
but how come it idled rough and then i filled it up with gas and added heat and fuel injector cleaner and it was fine for a while then it would rev up and die and after i replaced the fuel filter its back to just idling rough. will fuel injector cleaner help again?
Expert:  Chris (aka- Moose) replied 6 years ago.
Cleaner will not help in getting contaminants like rust out of a fuel injector.