I have a 85 Gsl-se the problem just started when it got cold. It is ok when it just starts up but when it is warm it idles up and down real bad when sitting at stop light. Has anybody else had this problem.

 

check for vaccum leaks. They are masked when the engine is warming up because it injects extra fuel. Spray wd-40 around the small hoses above the engine and see if it rises or smooths out, then you know you have one. Usually hoses get cracked and leak after many years and miles.. This may not be your problem, possibly bad wires/plugs.

 

do you mean surging between 1500 to 2000rpm or just "hunting" between say 600-800rpm. The whacky surging is usually caused by the TPS (see the other GSL-SE idle thread). My rough idle went away when I advanced the timing a little and swapped the bypass air valve. Can't say for sure which of the two solved it but it went away after I did those two things.

 

It idles at normal around 800 then surges up to around 1400. But it don't do it all the time. It's might not hurt anything BUT it sure is annoying.