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I have a 1988 f-250 with the 5.0/302 efi and I have had problems lately with my engine. So the problem is that while sitting idleing if I step on the gas it hesitates and misses just a small amount but for as when I'm driving say I drive around and then come to a stop sign as I let off the clutch in 1st it bogs down and I have to feather the gas so it won't just shut off and same thing in second gear but after I get to 3rd it clears out so in 1st and second under 2000rpms it bogs coming off the clutch and after driving around for say 20 min it'll just shut off and wont want to start again but say I wait a day it'll start first time no problem I've gotten a new fuel pump replaced the Ecu and the o2 sensor and my fuel pressure is where it should be.
Other possibilities include the throttle position sensor. You can test it with an analog ohm or volt meter by hooking its leads to the wiper and one side of the variable resistor. The resistance or voltage should change smoothly as you open and close the throttle. You test the resistance by pulling off the EEC connector, and test the voltage with the key ON engine OFF. Either one should be able to tell you if you have dead spots on the sensor.
Your 1988 F250 has electronic fuel injection that uses a computer. Run the KOEO tests and stored code display. See what it thinks is wrong.
There is a CM code for an erratic or missing PIP signal. hint:"after driving around for say 20 min it'll just shut off and wont want to start again" Classic bad PIP symptom, but do the diagnostics first. Obviously throwing parts at the problem has not fixed it yet.