Engine Performance problem
1991 Ford F150 V8 Four Wheel Drive Manual 74000 miles
I have been battling poor gas mileage on my truck, I average 12mpg at 90% highway driving. It has a 302 engine. At first I was getting egr fault codes, I removed the egr, blocked it off, and installed an eliminator to prevent the check engine light. This took care of the egr codes but now the ecm is giving code 44 " AIR system inoperable". Under heavy acceleration the truck surges like its starving for gas. I haven't checked fuel pressure but I did check the regulator by removing and reattaching the vacuum line. The engine picked up when removed and slowed when re-attached, so I figure its working? I changed pluggs, wires, cap, rotor, air and fuel filter. Still no improvement! Any ideas?