Engine wont run unless full throttle and wont pass 1200 rpm
 

Hey guys I'm new to the cummins world I have a 95 12v that is giving me headaches I can only get it to run if i hold the pedel down all the way and then it will only run at about 1200 rpm it sounds great when it's running but as soon as i let off the throttle it dies i have replaced the pre filter,fuel filter,lift pump deleted the fuel heater I took the sending unit out and cleaned the screen blew out the lines and replaced the factory lines with larry b rubber ones I also put in a new overflow valve too I'm out of ideas if anyone has any input I would greatly appreciate it I haven't got to check the fuel pressure yet but I ordered a gauge that's next on my list

Maybe the shutdown solenoid does not lift the lever high enough or the shutdown lever has slipped on the shaft?

Take a look at this thread where a guy had the opposite problem.

I read that and removed the fss and have it wired up tight so that's not the issue

OK, then I would check for air bubbles in the fuel- try opening the water drain on the filter with the engine running- route a transparent hose back to the filller neck.
There should be no bubbles.
(I had bubbles from a chafed line in the in-tank module. Drove me mad)

Then a pressure check, or test the overflow valve with a regulated air supply.
(Valve on the bench, apply air pressure until it opens, there should be no leakage and opening should occur at minimum 25 psi, better 31 psi- this is the max flow pressure of the lift pump.)

I will give that a try and fully get being drove mad by this I appreciate the input