I have a 90 Sunsport with the 351 PMC.
Took the boat out 5/18. Tested it. 3 people. Ran great
Took the boat out 5/26.. Different story.
***First*** the boat would do nothing with the key in the ignition. Thought the batteries were completely dead, but even a jumping the boat didn't help. Did the old screw driver to the starter relay, BAM! Problem solved. Awesome!
***Second*** Loaded up some friends, headed towards the spot on the lake I like to start taking newbies.. After about 2 minutes @ 26mph, boat sputters... then dies. RPM's dropped quick, boat came to a slow down, then sputtered at idle. Tried giving a little gas when it was sputtering at idle, didn't do anything. Wait about 15 seconds, boat starts up, runs at speed for about 15 seconds, then does the same thing. Cycle. Rinse. Repeat...
We were able to get it to run "fine" later, we took apart the cap and rotor. Tightened the non-working temperature sender unit (or gauge.. one of them isn't working). Not sure which thing specifically helped, but any input would be helpful.