I have a 89 mpfi DX and have been having some idle problems the last few months. When the car warms up and I come to a stop the rpms will drop almost to zero and stay there for a few minutes, then back up (like when the fans kick on). I notice it does this much more often when its hot outside vs at night when its colder.

Also the car overheated about a month ago due to a small tear in the radiator hose. I replaced the hose and bled the coolant system. Now when I'm driving the car and let off the throttle, around 1.5-2k rpm the car will buck or stutter like its missing a little bit.

I didn't have the stuttering problem until the car overheated and I replaced the rad hose. Its like the cooling system has air in it, but I have bled it multiple times according to my manual.

I've had the low idle problem for a few months now.

Are these two problems related? What should I look at to fix the problem?

 

did you find any oil in the coolant? and if and when you change the oil did you see coolant in it?

if you have access to a compression guage i would do a quick compression test to see if the head gasket is shot.