Ford Repair: stalling, fuel pressure gage, fuel issues

Question
I have a 85 F150 with 5 liter fuel injected engine and automatic transmission. Truck has always started with first turn of the key and always runs strong. Still starts on 1st try but lately it has started to intermittently stall when stopped in traffic and also stalls when parking before i put it in Park. I have replaced in the last two weeks the following: spark plugs, cap and rotor, ignition coil and module, and fuel filter and i set the timing. Now the truck will not go above 35 mph and stalls on hills above a 45 degree angle.  engine sounds like it is "missing" to me.  spark plug wires are in good condition so did not replace those.  air filter is clean.  dont know what else to do??

Answer
Look into fuel issues. Get a fuel pressure gage and attach to the fuel rail test port. You should have more than 35psi (you should double check that figure in your service manual.) See how fuel pressure reacts to throttle movement. It should stay fairly stable and not dip too much. Consider removing the injectors and having them cleaned. Or get a bottle of FI cleaner to add to the gas tank. This all presupposes that the fuel pump, fuel filter are letting plenty of gas to the motor. Have a look at: http://www.docinjector.com/