My 2001F150 is giving me fits. Every now and then it will start reving up and down RPMs go up then down causing the truck to buck, AC quits cooling and just acts weird. It will stop as suddenly as it starts, might go days without doing it might go minutes. The only code it ever throws and it doesn't throw this code everytime, code P1451 something about the evaporative vacuum control sensor, I think it throws this code due to the erratic running of the engine. HELP!

 

Your code says there is a vent control solenoid circuit issue with the fuel tank system.
It may or may not be the cause.
Fix the code then see what happens with the motor.
.
The idle control is somewhat complicated in that when A/C is on the PCM is signaled to account for the extra load by opening the IAC a bit more on the 'average'.
If there is an issue outside of this the A/C can be affected.
First thing is to clean or replace the IAC to be sure there is no sticking condition.
The fuel tank has a vacuum pulled on it to test the system for being tight to the outside world as part of emissions design.
The vent clears the vacuum and pressure as part of the testing that goes on.
.
Otherwise do an inspection of all the rubber connected to the intake system for rot, splits, etc.
Check that the throttle body bolts has not come loose.
Good luck.

 

My 1999 did just about exactly that same thing. It was the air filter plugged!