1987 124 suddenly misses on Interstate?

I have a 300E that out of the blue will begin to run rough, misses, and backfires and losses power. This happened to me this morning at 70mph finally pulled off the road because my speed kept dropping down. The engine stalled out attempted to restart nothing. Noted white smoke coming out of my tailpipe. After about three minutes started up, huge cloud of whitish smoke appeared, ran rough for a few 30 seconds and then it was OK again except for a couple of burps at high speed. Does anyone have any idea what could cause this? Electrical, fuel, other?