I've got a 1990 toyota pickup with a 3.0, I recently bought it off a guy and it ran fine when I got it. A couple of weeks in a few codes came up and i changed the MAF sensor that cleared all the codes. Truck now runs again but backfires under load and is running extremely rich, I checked the timing it was about 30 degrees off and idling about 1200, its now set back to 10 and idles about 850, it's still running rich but not as bad. I've checked all my vacume lines, i confirmed that the intake is sealed properly and no un-metered air is getting in. At this point I dont know what to do next. Any help would be greatly appreciated.

 

Did the Toyota part number on the new AFM match the old one? These AFM's were used in several different vehicles and are calibrated differently.

 

I'm not sure I'll have to check it I did pull the cover plate and try adjusting the AFM but it didnt get any better learning it out. It's a mood point now while fiddling with it I guess one of the pops blew out the head gasket, cause its dumping coolant now. So it's down for the count until further notice.