Just last week i noticed the 4runner cranked over a few extra times before firing up. A lot of nice thick black smoke dumped out the tail pipe. Ever since it seems to be running rich. Even after i wipe the excess carbon from the tailpipe it reappears quickly.

There's No check engine light and it seems to run smooth otherwise. The exhaust does have a "rich" running smell also.

Any ideas on what the culprit is or how to fix it?
I'll probably reset the ECU and see if re-adjusts to solve the poblem.