I have a 1989 Granmarquis 5.0 engine with platenium spark plug, no vacuum leaks, new wires, pcv valve,air filter,fuel filter,ac/heat works, but still my car has a minor,minor shake. What I mean is wentI stop at a light, the car is at an even stroke.The car is smooth as hell but after a few seconds the car gives me this minor shake. I know it is not much but I want my car to drive like a dream machine. It feel likeaminor uneven stroke. The car has alot of power for 159,000 miles. I plan to paint it and fix the interior. [img]smileys/smiley6.gif[/img]Any comments will be appreciated.

Do the rpm''s drop like it wants to stall out?

What do you mean. [img]smileys/smiley5.gif[/img]Is it to adjust the idle speed screw. I am not to familiar with that procedure can you give me more details please.

No, don''t touch the idle adjustment. No procedures yet. I just want to know if the engine feels like it wants to stall when you say it gives a "minor shake". Does the car have a tachometer? If so, does it flucuate during the "minor shake"? I would clean out the IAC (idle air control) for good measure. Can''t hurt. Let me know.

By a minor shake, I mean like a small uneven stroke.It is not that much of a difference, but I will attacked my tachometer and make sure it is up to stek. I might have to adjust the idle but that will be my last resort. Also, the IAC is a new one and so is the throttle position sensor. Their is no flucuation at all but the minor shake. Any more ideas will be appreciated.[img]smileys/smiley3.gif[/img]

Has the throttle body butterfly valve been checked? There maybe deposits around the housing preventing full closure. Also, deposits on the EGR valve can cause the same symptoms.


Cheers.

Ok, Ihave clean the throttle body with carburator cleaner to remove deposit but the EGR i haven''''t yet. So , I will remove it this weekend and see what happens. I will get back to you with my answer as soon as Ido it. Anymore suggestions are appreciated and thank to everyone who is responding to questions.https://www.mercuryforum.com/smileys/smiley12.gif


Edited by: pdman

Cleaned out the EGR with carburator cleaner and it help a little. I lower the idle adjustment screw a little more at about 625RPM from 675RPM.To do this procedure you mustconnect an RPM meter andhave your car on Drive with the emergency brakes on.It is at the best that i think i am going to get it. So, Iam going to leave their and see how it responds.Thank you again for your responds.