My buddy has a cruisers 340 with 8.1 mercruisers. The port engine only turns 3600-3700 rpm but the starboard runs to 4300. The exhaust smells like unburned fuel on port side as well. We see no gas sheen on water however. Any ideas on what the problem could be. We are thinking maybe one cylinder is down but I would think we would see a gas sheen in exhaust. As well we definitely have an issue with debris clogging filters in starboard side(the side that runs up to 4300). The problem is it appears there is no way to remove pickup tube to see if the pickup tube screen is clogged(if there even is a screen). That engine will run fine for 15-20 min then start to die out. It will idle but won't run up. If we let it sit for 5-15 min. It will run fine then do the same thing. Are we missing something about removing pickup tube? It can't come straight out because the deck is right above it.