Alright guys this is driving me nuts. I have an 1990 F150 with a 302V8 M50D trans. Im pretty sure i have a bad head gasket and im hoping for someone to tell me im wrong but here is whats going on with the truck: Tailpipes smoke for a little bit after i shut it down. It leaks oil slowly it drips off the bottom of the bell housing, right when you turn the engine off and you hear a sucking noise like a piston pulling in air. when its cold sometimes it misfires when you start it and it wont run normally till its hot.(it acts like a cold two stroke motor) The truck has never died or overheated for the 6 months ive had it but i think it has had a considerable loss of power since i got it. I would also like to know if it would be a terrible idea or not to dump some head gasket fix in there. oh and i found out the truck has no pcv valve there is just a hole in the valve cover where its supposed to be