1990 VW Golf 1.8L Digifant II fuel injection - when cold, idle fluctuates between 1000 and 2000 rpm for about 2-3 minutes (summer time) then drops down to normal idle and runs fine after. Replaced distributor, coolant temperature sensor, spark plugs, and oxygen sensor. Swaped out with another car the computer, air box, idle speed motor. I've run injector cleaner in the gas tank with no difference. I'm stumped

 

the idle goes to normal after 2-3 minutes? Well it is a 1990; is there any running problems when you're driving??

 

The car seems to run fine after the initial warmup.

 

I've seen older cars do that from time to time. I think they make some gumout or some other cleaner that should take care of that. check with auto parts store.