Am not sure but don't think the '86 had a carb. In any event, try Red Line fuel treatment. Available from this site. You will like the results. BTW, at some point a large, and even perhaps HUGE cloud will emit from the car's tail pipe. Don't be alarmed, it's just years worth of carbon build up being ejaculated out the tailpipe.
'00 ML320 "Casper"
'92 400E "Stella"