New to the forum, hoping for some insight. 2010 Rienell boat, 4.3l GL-J eng., SX-A 1.89 Penta drive. Nightmare boat!!! Engine replaced last fall, due to catastrophic fail. dealer said overheated, but didn't say why it did. Ran good for 5 days, then started having issues. Brother brought it back to dealer who replaced engine, they told him they replaced cap and rotor (2 plugs not firing), all good. He brings it to the lake, on the lake for 10 min., engine goes from 3800 rpm to 1200, idled back to dock. I removed cap, piece of cap material impeding center contact. Clear material/bakelite plastic, reinstall. engine runs the same, can hear pinging in engine. Back @ dock, I remove plugs, starboard side all black and wet, port side all clean/tan and dry. Replace plugs, good for 10 min., then same thing. Not ignition, not compression, Ideas? gonna check carb flow soon, just putting out feelers to see if anyone seen this before. Could plugged exhaust be cause? Thanks in advance, Neil.