Hey,

I have a 2005 GMC Canyon 2.8l 4 cylinder with 116,000 miles. I have a check engine light on with codes p0300 and p0506, which are random misfire and low rpm codes I believe. Has a rough idle.

I was wondering if anyone has any suggestions in which direction to go. I am thinking a dirty throttle body possibly, which I will be cleaning when I go back out for a can of cleaner. I looked at stft and it was staying around +3 to -2. I was hoping for a high number so at least I would know to look for a possible vacuum leak or something. The idle jumps up and down around the 500-550 to 600 range. I unplugged the maf sensor to see if it would maybe default to something and get better to possibly tell me if it was dirty or bad?!, but it didn’t help anything. It was showing around 3.5 g/* at idle but not sure what it should be. The truck seems to run fine when it gets going though as far as I can tell. Any suggestions or anything to look for in the live data that could help narrow something down are definitely appreciated. Thanks

Idle jumping around like that tells me something is wrong, and likely triggered the P0506 .

How many miles on the current spark plugs and wires?