350MAG EFI running in 3-4K RPM range suddenly drops to idle

[northern baja]

Yesterday I encountered 6 to a dozen instances where RPM suddenly dropped to bassicaly an idle. Once I lost plane and the boat settled down in the water, I could hit the gas and run back up.
Knock senser?

[aslack99]

Sounds like a fuel delivery problem.My buddy had a boat do the same thing and it was a problem with a float where the fuel pump lies.

[SmokinLowriderSS]

On an EFI, I'd be suspicious of the TPS, Throttle Position Sensor failing.

[northern baja]

A real joy. It would be nice to get 15 minutes of trouble free boating between repairs.
I just got this boat back from the marina. I had a small oil leak that they found to be a pin hole in the timing cover. They had to remove the engine to replace the cover. $900 later I ot the boat back. Narrowly avoided an accident in the marina because the shift linkage was loose.
So the fact with the whole engine being removed, it could be anything. At this point I could take it back to the marina, but you know this won't be anything they touched, so another ripeoff repair.
$900 for a timing cover replacement...who woulda' dunk it!