The part about the odd shifting reminds me of some other threads I've read on here, but I don't recall if there was a common solution.

 

Thanks for all the great responses, looks like I have more diagnostics to do.

That being said, do any of the tuners show real time live stream data? If love to be able to see what's going on inside.

 

I've been down the clogged cats road, I haven't been able to dispel that but because of the timing I'm not confident in that answer.

It really seems to be temp related...as soon as that needle hits about 12 o'clock on the gauge everything seems to start lacking. Feels like it shifts into second almost immediately from a start and takes almost WOT to get any type of acceleration.

 

I have the same problem. Mine is an 03 F150 4.2L that runs great cold and looses almost all acceleration after 20 minutes of driving, especially if you shut the ignition off and restart. Not only is acceleration rough but it won't shift until 4k plus RPMs. No transmission codes, although that what all 3 mechanics believe is the issue. I have cleaned the throttle body, it has a new MAF, transmission has been serviced, New plugs and wires. My first mechanic suspected the cat so it has been removed to see if it was the issue. It wasn't although he said it was pretty clogged. Bad upstream O2 sensors maybe? But since it has no cat I'm led to believe the bad O2 sensors is another rabbit hole. Thoughts

 

So it's definitely temp related...since I swapped out the MAF sensor my MPG went to 14-15, and truck has been driving great...until I get to full operating temp (temp gauge needle at middle mark).

At this point, I am stumped.

 

I'm pretty much left to believe it's the PCM or Transmission solenoids. I am getting an fuel pump circuit code too but I am hoping it's just a solenoid. It goes to the transmission shop at the end of the month for a diagnostic.

 

Why would you ignore the fuel pump code? What is the code?

 

P0230. I haven't ruled the fuel pump out, however the symptoms align more with a transmission issue or a PCM according to both the Ford dealership and a separate mechanic I took it to. The PCM that's in it now is the second PCM the truck has had already.

 

Did you find the solution? I had a similar problem. Transmission shop ruled out the transmission as a problem. Looks like it may be the fuel pump after all. It has no Cat and a new exhaust. MAF is new and throttle body is clean. Fuel pressure was 35 psi, but the mechanic didn't say if that was cold or warm. It only acts up when warm.