Do you get any check eng. lights. Also a rich running car will tell the computer to lean it out. Maybe you could find someone with a test meter that will show all the sensors while the car is running not just a code if a check lite is on. I was also going to say a overactive egr but you allready done that. Also on the carb there is a rectangle cover held in place with a cotter pin it's just in front of the whole that the air cleaner rod goes, pop that cover and turn the jet looking thing 1/8 turn in at a time to richen the mixture if you get a check lite you have gone to far. It's a fine tuning thing on the ccc carb.