325i With Problem that comes and goes

[kgs6076]

Hi all,
I have a 1989 325i that has an intermittent problem. The check engine light begins to flash on and off and builds in frequency until it is on full time. It will stay on about 5 minutes and then begins to flash off and on until it finally goes off. The engine will rev up to about 1500 and back down on its own at times. And while the light situation is going on performance is decreased. This seems to happen most frequently on initial warm up or the first drive of the day. Afternoons, (after sitting parked for four hours) are never a problem. Does any one have any idea of what may be causing this condition?