recently purchased a 2000 ford f150 4.2l. started hesitating when i would try to accelerated stressed or when a.c on. if i drive it like a grandpa wont do it. filled up the gas tank and it completely went away. the second it went down to the 3/4 line, started hesitating again. mind you when it was full even with the a.c on and going 80mph on expressway it would not hesitate. please help!!

 

Have you code scanned it? Have you checked fuel pressure?

 

I had a mini van 20 years ago with a small exhaust leak that was directed toward the fuel line in front of tank. At low tank level, with return fuel being warm, I would get vapor lock in hot line and car would stumble.... Full tank never happened ...... its a long shot but something to check.