As stated in the title I have 1986 ford f-250 7.5L engine. Lately I have been having trouble when I am going up a hill the engine will shift from 1st to 2nd ok but when the RPM's get to about 3000 (which is about the normal RPM level for shifting that I have observed) it starts stalling and I let off the gas. If I try giving it more gas before it reaches idle level it will die. I usually have to feather the throttle until it down shift and then limp it to were ever I'm going.

I only seem to have this stalling problem when driving espially when driving up hill or over 35-40 MPH, but in park I can idle and even rev the engine for a prolonged amount of time and no stalling. Also I am no sure if this has any ting to do with it or not but I have to have my curb idle screw all the way tight. (holly- motorcraft 4 barrel carb stack i think)

please help!

 

I'll bet therein lies another symptom of the real problem, needing to have the adjustment set like that should tell you something.

 

It wanting to stall under load yet will idle and accelerate in park, sounds like a classic problem of it's just starving itself of fuel...fuel filter or float adjustment.

But having to have the idle set all the way up to keep it to idle dont make sense. Is your choke set right? When it's warmed up, is the ckoke plate all the way open?

 

It does sound like it is starving of fuel, and that could be due to a fuel pump failing. Or fuel filter or float level too low like Kevin said.

But, lets clarify what you mean by "curb idle screw". That is, I believe, the actual name of the screw that adjusts the idle speed - that is what you mean, right? If that is the case then you may have the idle mixture screws badly maladjusted. Or, the float level is way low, which would fit with the problem of dying out in gear.