stumbles when letting off gas

[monterey1962]

When I test drove that '85 CV today, the only real problem I could find with the engine is that is stumbled when you let off the gas while driving. Any ideas on a possible cause? The transmission felt and stifted good. Sorry for being so vague. I'll get more info to you guys when I get the car.

[85crownHPP]

Mine used to do that.... over time as a tweaked things it went away... never pinned it to one thing. First thing I would look for is a sticking or clogged EGR valve. Checking it out isnt too hard...
Also if the EGR cant 'vent' the vacuum away fast enough, it will stumble as the valve closes slower than it should.
The EGR valve is supposed to close immediatly once you let off the gas... it should always be closed at closed throttle, so if your idle is rough this could also be affecting that.
Hooking a vacuum meter to it should tell you if its a venting problem or not.

[monterey1962]

She idled nice and smooth. I'm sure it wouldn't hurt to give it a good tune up. I should get to it this week. I'll check the EGR and let you know what I find.

[boXman]

Run some seafoam thru it, too.

[monterey1962]

The '85 ran like shit this morning so I couldn't drive it to work. I'm getting a new fuel filter in tomorrow.

The engine sputters and tries to cut out when I accelerate. I haven't checked the EGR, yet. Anything else I should be looking at? If I can't get this engine running smooth the car will be gone. I don't have a lot of money to put into it.

[Paul_]

could be a vacuum leak

assuming the lines haven't been replaced in 20 years or so, they're probably all brittle now