I have a 92 GMC sierra with a 350 SB the engine has recently become unbalanced at low rpm's. I dont think the throttle body is clogged as we have cleaned it, and seen no results, it seems to have just done this recently, also some times the oil pressure guage drops on occasion and the check engine light comes on, but its not short on oil, pretty sure its the oil pressure sending unit, its just a pain in the *** to replace and i havent dont it though i have the sending unit in hand.