I have a 97 F150 that's not my daily driver. My problem is that when I let is set for a few days it becomes very hard to start the first time. After the first initial start its fine the rest of the day no matter if its hot or cold. It runs great doesn't seem like it starving for fuel. I have replaced the fuel filter and that hasn't helped. I know its not the IAC because its not that old. Could it be a check valve in the pump that is slowly letting the gas back into the tank? I'm just stumped because it runs good and starts fine excpet when I don't drive it for 2 to 3 days. One other thing when it does that I have tried to prime the pump a few times and let it set for a few seconds and that doesn't seem to help too much. It does eventually start but definitely not like it should.

 

if you can cycle the key 3 times and it starts up you fuel pump is bleeding off,it you crack the throttle a little and it starts its the iac.