2004 f150 MAF Sensor?
 

I started my truck the other day and it didn’t turn over nicely, took a while to start up and then when it did, a puff of white electrical smoke came out of the AC vent. With the air conditioning on the engine rpm surges from around 800 to 1100, but when it is turned off it idles just over 600 and drops down to the point where it eventually stalls and fires up again. I also show a lean engine code. 2004 f-150 5.4L 180,000km

Any help is greatly appreciated, thank you