When I am crusing at above 40 mph, and I let of the gas the engine hesitates and loses power for a second. It only seems to happen after 40 mph. It also occasionally sets a code 44, lean exhaust, but only about once every thousand miles. In addition the car idles rough and when Im driving at 1200-1300 rpm it also stumbles a bit.

It is an 88 350 with 85000 miles. I obviously have a fuel or o2 problem because of the code 44 but it seems as though there is an additional problem as well.

 

I'd check the TPS voltage first. Then maybe the IAC needs a good cleaning (use throttle body cleaner). Then you should probably replace the O2 sensor (depending on how long it has been since you last replaced it). Finally, perhaps if the EGR valve is stuck open it is recirculating the exhaust and burning off all the fuel to make it lean. Don't know if that's possible or not.

Anything we ought to know about your situation that would be helpful to us? Like any mods or maintainence recently done to the car that might have caused this?

 

I just did a complete tune up 5000 miles ago. New cap, rotor, wires. plugs, coil, pick-up coil, o2 sensor. It also has a mild cam headers and stuff but I doubt that would be the cause. I am cleaning the IAC and fuel injectors right now.

 

cam specs? TPI or TBI or carb? year? Speed density or MAF? Stock program? I'd be willin to bet your cam is too big and you need to get your computer tuned for the cam