Freinds 96' keeps stalling

[Gray 5.9]

My friends 96' dodge stalls when put in gear(forward or reverse). The idle was low(around 500rpm's) so I adjusted the throttle screw to 800rpm's with it in park, put it in drive and romp on the go pedal lightly with my foot holding the brake and it would stall the engine, crank it back up in park and the engine would go back too 450-500 rpm's. I double checked the Idle screw ,making shure that it hadden't backed off, and it was tight. So I idled it up a little more in park. I put it in drive again. The RPM's where holding steady at around 700-750 RPM's. So I hold the brake again, romp on the pedal again and it stalls again, this time when I cranked it back up in park, the RPM's where at 900-1100 . I checked all the mounting screws where the idle screw is adjusted and all where tight. Would the fuel relief valve on the injector pump cause this, the truck has 128,000 on it . Thanks for any answers

 

[Joe G.]

The idle should be at least 700 RPM with it in D and the A/C on with the engine at operating temp. If that doesn't do it, then you need a fuel pressure gauge. If the pressure is low (less than 20PSI) you either have a plugged fuel filter or the overflow/return valve spring may be weak.