Having issues with no power when traveling up hill. When I press pedal going up hill truck downshifts, reaches 3000 rpm but it can't gain any speed. Ran the OBII scanner. At first I had a P0101 and P0102 code. Checked air filter, all good. Cleaned mass air flow sensor. No noticeable leaks on the intake. Nothing changed. Truck had the same condition. I replaced mass air sensor. This cleared the CEL. However, did not fix the issue. Now I have pending codes P0101, P0102, and a P0300 (misfire) code. Checked voltages to the MAF sensor. 12V from battery is good and 5V from ECM seems OK. Ground is good too. I am still getting exhaust out of tailpipe and it appears OK. So I don't think it'* a clogged Cat, but I could be wrong. Truck has 260k miles. Anyone had this issue before? Any advice is appreciated. Thanks.

Are you sure that you don't have P0301 P0302

It gave me a P0300 multiple misfire code. I will add that code is currently in pending status as indicated by the ODBII. Not sure if that helps much.

A P0300 means more than one cylinder has been misfiring. That code is accompanied by the offending cylinders such as P0301, P0302 etc. Did you read the tool correctly?

I thought that I did but I will have to check again to make sure. More to come. Thanks for responding.

What engine are we talking about?

It is the 4.3L engine.

Let'* be sure what codes we currently have.