My truck is a 1994 Ford F-350 5.8l EFI 351w with C6 auto transmission 52,000 miles. We have been hauling a truck camper for the past 15000 or so. Since yesterday, once the truck has warmed up, when you step on the gas and accelerate, even a little bit, once I let my foot off the gas, the engine stalls. If it is not too warmed up yet, it will sputter, but when it is at operating temp it stalls immediately. It does in park and in gear. There is no CEL, but I checked codes and I got 334 (Egr).
I replaced the EGR valve about 1000 miles ago (March), and also replaced the EGR tube and put on a new throttle body back in February.
Also, I had the fuel system serviced in January ( new fuel filters, fuel system cleaning)
Yesterday and today I replaced IAC valve, FPR valve, EGR Valve position sensor, and the TPS. After replacing those parts, there is still no change and the engine still stalls.
Also, the engine starts back up normally after it stalls.
After this, I unplugged the MAP sensor, which caused the engine to run rough, but the engine did not stall after I unplugged it.
At this point I am at a loss. Hopefully someone has some ideas. Thanks.