high idle (+ fluctuation) only when warm

[Oolop]

1987 325E M20B27

from cold to warm/optimum temp (needle right in the middle) it idles fine. as soon as it reaches optimum temp, THEN it begins fluctuating from normal idle (~700) to ~1000 rpm. sometimes it just stays at 1000 rpm depending on the outside temp/weather. could it possibly be a vacuum leak since a high idle usually means that or even my TPS? possibly even a coolant temp sensor? i've done research but everything comes up with different symptoms than mine. thanks for all the help!

[jlevie]

Intake leaks are a distinct possibility and should be the first thing checked. Have a shop run a smoke test on the intake.

[long tall eta]

had pretty much the same problem but my idle was much higher. it was a combination of icv, tps, and the maf. took it to guten parts and service and he gave her an all around adjustment and now i'm good to go. no parts, just service. these cars are old and need some tlc from time to time on their intake systems.