engine acting up

For you deep water guys. What’s the first place to start looking for when at an idle or part throttle, you floor it and it falls on its face like you cut the power. Started this towards the end of a long muskeg day with lots of stuck. It also started to die just sitting there and idling like it missed a beat then died. Thinking throttle position sensor but heard throttle safety switch can be common but only here and there and if I pumped and feathered the throttle it would sort itself out. I guess I’m asking to see what you guys have found and I hope to not case my own tail around.