I just want to see if anyone else had/has this problem , or perhaps knows what's wrong...

If I drive on the highway for an extended period of time, and then i drop out of 5th into neutral to cost into a rest stop or whatever....the rpms go nuts!

4,500 rpm in 5th
-neutral-
1,100
2,000
1,500
800
2,000 (stays here for about 15 seconds)
then a normal idle @ around 1,100

anyone know why?

 

Rich, lean, rich, lean, rich,lean?

 

do u have a afc?

 

i have no afc or anything like that.

 

How long is it staying at those different RPMs?

When I am cruising in 5th, then stop for a light, the car idles high (I'm not sure exactly what RPM) for about 3 seconds, then drops to normal idle.

 

I'd assume that dropping the rpms is alot for the IAC (idle air contol) valve to handle and it is just adjusting slowly. If the car has higher milage it might be worth the time to remove it and clean it with some carb cleaner.

Mattj

 

Does this happen when your car is first warmed up or only after extended drives?
I've had the same problem but mine happened right when my car when warmed up. I adjusted the throttle screw on the throttle body and problem was gone. You have to chip off the seal to adjust it though.

 

Okay, I just got back from a friends house and was paying attention to the RPMs when I came to a stop.

-Clutch in, engine drops to 1500 rpm. As long as the car is moving the revs won't drop below 1500.
-A few seconds after the car rolls to a complete stop, the revs drop to 1100 rpm.
-A few seconds after that, the revs drop to 800 rpm where it will idle all day, unless the A/C unit kicks in.

What yours is doing sounds quite weird.

 

Throttle plate might be sticking a little. Pull the gas pedal back with your foot to see if it drops. Or, just clean the TB butterfly.