Volvo: poooor mileage and performance in cold, mass air meter, vacuum leaks

Question
I know you said 240's but i really need a good answer i drive a 740 gle 1986 and i am just recieving horrible milage like 12mpg and ive tried vacuum leaks replaces 2 hoses and then i did some injector cleaner and still didnt work any suggestions?
and also in the mornings i will start it and it will idle and i have to let it warm for like 1 min then switch gears or it will die and while running i am getting real poor performance until but when i drive maybe 5 or 6 miles it gets back to having normal performance

Answer
Sounds like you might have a bad mass air meter, which causes those problems.  I would also have your oxygen sensor checked and replaced if neccesary.  Both those devices help the computer regulate fuel timing consumption.  A failure in either or both sends the computer into default mode, causing is to use much more fuel and run very rich.  Good luck!