lumpy tickover

[gordonmorrison]

hi im new to you guys ,as my Audi 80 cab is always parked in France and does nt get much use. It starts on the button but after a while the revs jump up and down sometimes to almost stall and then back up to 2000 or so. Ive fitted new rotor,cap,and the themostat kicks in at about 85 to 90 but the car seems to run cool according to the temp gauge,aroung 60 to 65. The plugs are also new.I think it may be a sensor gunged up or stuck somewhere as it sits for months at a time. Any feed back appreciated. Cheers G