Hi there, I drive a 2013 F150 5.0L. Recently I’ve experienced the engine dropping RPM at idle, and then surging back to normal. There doesn’t seem to be a regular pattern to this. It developed to the point where the engine finally stalled during one of the RPM drops. It started back no problem. Engine threw a code that the Bank 2 Sensor 1 oxygen sensor was stuck full rich. I replaced the sensor. The problem persisted and was getting worse. I had the MAF sensor replaced and the problem went away for a week or two before returning again.

The other day I got fuel and the engine refused to start afterwards. At that point it threw P1450. After about an hour of sitting there scratching my head I tried to start it again and lo and behold it started no problem.

I have already checked the Purge valve for leaks and operation and it checks good. Two days later and the engine is still starting, and is not surging like it has been.

Looking for someone a lot more experienced than me to suggest how to troubleshoot.