850 seems to want accelarate by itself a la Audie 5000

My 850 (1993 GLT) does a similar thing......The rev counter will show high revs although the engine is only ticking over, This can be disconcerting as sometimes due to surrounding noise you can't hear the engine. My car has only done this while stationary on tickover. AFAIK the rev counter reads correctly while the car is in motion. This did also effect the other instruments as well, as the speedo, petrol, temp dials were also doing a dance at the same time. The car has done this twice in the five years I owned it. No fault codes to indicate what it was/is

ttfn......Alisatir

Bad ground connection somewhere I would guess, start by checking the ground strap between the engine and the body.