2001 F150 4.2L V6 with approx 108k miles has a starting issue. Here's what i know. Has been starting hard for over a year, now its time to sell and i need to fix the issue. Always fires right up first thing in the morning after its been sitting 10-12+ hours. Runs and idles as smooth as new. Once it reaches operating temp and is turned off, it will restart just fine within about a 10 minute window. Any amount of time over about 10 minutes, it will turn over for 5 to 10 seconds before finally starting (it will start every time) and sputters and coughs as it has flooded itself and then everything smooths out and all is well. Been to the dealer 2x and they don't know whats wrong, but figure they can fix it for about $1400. What I have done, new fuel pump and filter. New air idle control valve, new cam position sensor, new throttle position sensor, new evap canister purge valve (sounded like a vac leak was occuring), injectors cleaned and tested, checked the relays all seems fine, have spark as soon as the key is turned, fuel pressure always at schraeder valve always in spec (regulated or unregulated values both). Can't remember what else off the top of my head.... Problem has been occuring for over a year, and seems to be temp related (not sure how long it takes for the entire engine block to cool, but im guessing something over 9 hours as it turns over for a long time after its been sitting parked while im at work). I'm at the end of my rope... possibly something opens or closes as the engine heats and won't re-close or re-open until everything is completely cooled... ANY help or suggestions (other than scrap it) would really be appreciated.
Thanks
Jeff