I have an 88 (F150) It's idling rough then stalling... Sometimes doesn't start at all. And has little to no power when trying to accelerate. It's always been worst when it's around 40 degrees out, which is now warmer or colder is less problematic. When it's idling it makes a low moan/hum that cycles Abt 1hz. It gets louder and louder then when it dies there's a brief sucking noise, but the moan continues about 1 second after it dies. Sometimes the pitch goes slightly higher or lower. I just changed the fuel tank reservoir/valve and the s belt. It's been having this problem on and off for a few years... But it's to the point now where not starting at all.

*Edit: also cleaned the IAC
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Start by checking fuel pressure. If you haven't changed the three capacitors in the ECM, it would be worth removing the cover and look for any bulging or leaking electrolytic capacitors. Very common problem with the old Fords.