Windstar hard to start when warm

1999 Windstar stats and runs fine when cold. After up to temp it is hard to start. Sputters and backfires. Nurse it and baby it and it will eventually 'catch' and run fine. If you let everything cool down it will start and run great.

The only codes I am getting are P171 and 174 (Lean fuel). Intake gaskets have bee replaced along with most of the gaskets from the air filter to the intake. Also changed to PCV Valve/lines, camshaft and crankshaft sensors, fuel filter, and temp sensor.

This is a full ramp conversion for my wife and I can't afford to replace it but I'm running out of ideas!:banghead:

I wonder if your intake gasket replacement included the all-important hold down bolts and grommets? If the grommets were not replaced, little has been accomplished. Its possible that while an engine sits for a while, excess oil will run down and do some "sealing". Then upon start-up and warm up, this sealing film gets "sucked away".

There are other locations for air leaks that can be elusive .... in the vacuum power system, that includes the brake booster for example.

Happy hunting!