For the last several months my truck has had a gas smell in the cab, smoke under the hood coming from the valve cover, smoke puffs from the oilf fill cap,and oil in the pcv valve system. Ive heard it knock a handful of times and immediatly let off, but ive heard that its probally blown already if i could hear it. Ive used datamaster to help do every tune up possible and it runs alright but is missing its full punch while under boost. I guess the next step is to get a compression test to know for sure. Any thoughts?