'87 Towncar

Can someone please help??? My Towncar runs very rough at an idle in gear. If you know or have an idea as to what might make this happen please let me in, cause I am goin nuts :banghead:

Sounds like a vacuum leak somewhere, maybe the main vacuum line to the brake booster.
Is the problem just when the brake pedal is applied? Try it in D or R with the parking brake locked rather than the brake pedal to see if the brake booster is causing the problem.

Does it idle worse when you pump the brake pedal? The brake booster consumes vacuum when actuated repetedly.

Other than vacuum, normal wear on spark components will cause the problem you describe. If you havn't replaced your spark wires and other high voltage parts for awhile it's a good time to do so.
You need to rule out the obvious and most likely causes before moving on to the more expensive and difficult to diagnose parts/causes.

will get back with you on this, checking on some of these ideas, thanks alot.

Does the vehicle stall? When was the last tune up? was the Air filter changed?


Your question is very vague, do you mean when you start the car and not in gear it runs rough? Or is it when your in gear not moving?

I apologize. I felt my explanation was quite clear. Runs rough (like wanting to die) at a stop light (at an idle in gear. As soon as I take my foot off the brake and apply the accelerator it evens out. Thanx

I apologize. I felt my explanation was quite clear. Runs rough (like wanting to die) at a stop light (at an idle in gear. As soon as I take my foot off the brake and apply the accelerator it evens out. Thanx

Yeah, that's what I got from your OP... which makes me suspect the brake booster however, tune up parts can't be ignored either.

With the 5.0l engine there are 2 common problems I suspect,

1. The IAC valve. Idle Air Control Valve does exactly what it's name implies. These can get gummed up with junk and cause erratic idle. It is mounted on the back of the throttle body.

2. The TFI module. Thick Film Ignition, uses a silica type film to control the ignition IIRC ( do a google search there is probably more info on it). There was a recall on this part due to it overheating. Causes car to be hard to start, run poorly and stall. This is mounted on the base of the distributor and you need a special socket to remove it.

Thanks will keep that in mind also.

Can someone please help??? My Towncar runs very rough at an idle in gear. If you know or have an idea as to what might make this happen please let me in, cause I am goin nuts :banghead:


Thanks for the info because I have been having the same problem and a major tune up wouldn't solve it. Does it idle a little better in the summer? I'm trying to restore the car now and I have some black smoke coming from the exaust on top of that.

This is mounted on the base of the distributor and you need a special socket to remove it.

I'm having ignition problems and am wondering where I can find the socket for this.

I have other questions regarding the ignition but I'll make that a separate post. Thanx for any info.

my 87 towncar stall as soon as i press the gas peddle. this happen all the time. the car will not stay running, someone help:banghead:

my 87 towncar stall as soon as i press the gas peddle. this happen all the time. the car will not stay running, someone help:banghead:

sounds like a bad idle/air control. had the same problem with my friends 88 town car. check that out

With this age of vehicle tighten the bolts for the intake manifold. Then get a can of carburetor cleaner and spray along the intake manifold on both sides. If this smooths out the engine replace the gasket.Try sticking a golf tee or small bolt in the vacuum line to the EGR valve it maybe sticking open. After testing remove the plug and replace it if defective. Unplug the hose to the vacuum booster and put a bolt into it. If this works buy a rebuilt canister.
These are some cheap tests.