Ford Repair: 5L F-150 dies after start, dual tanks, fuel pressure

Question
Dennis,
Thank you for volunteering your time to help us in this way. My daughter has a 91 F-150 w 5 L dual tanks, 150,000mi plus. She emailed me that it starts, but dies, but eventually runs okay. I am unable to contact her (we live hundreds of miles apart) right now, so do not know if it starts/runs okay once it is warmed up. She says that sometimes it starts/runs fine (like when she took it to the mechanic), sometimes takes up to five tries. Has to rev engine to keep it from dying sometimes, but not always. Lives in Vermont, has had lots of rain lately and truck sits outside. Has had battery and alternator checked. She wants to know what to expect when she takes it to the mechanic. My first thought was to put the “fuel system anti-freeze” in the tank and keep it filled. Any help is appreciated.


Answer
The problem could be a sticking idle control valve, fuel pressure issue, or several other things. Checking fuel pressure will be a good start, but getting it to act up while in the shop may be the biggest obstacle. Checking for PCM codes is best too. Might lead to the problem.