Is this EFI Pro Boss? If so they can be cantankerous. If it was a carbed one, I'd feel comfortable advising, but I know just enough to know not to comment on the EFI Pro Boss motors. My best advice would be email or call Vince at Discount Inboard Marine. (803) 345-0996 www.skidim.com
If it is an EFI motor, and it was mine, I would personally pull off the EFI and coil pack ignition and replace it with an Edelbrock low rise intake manifold (EDL-2181), a Holley 4160 carb, and Mallory distributor and wiring harness kit from skidim to replace the aging and troublesome electronic coil pack ignition. My carbed 92 Pro Boss was never the motor it should have been until I replaced the 4010 carb with a 4160 and dumped the electronic ignition for the mallory kit. It has purred like a kitten for a decade now since doing so.
1992 Supra Mariah - Red
PCM 351HO 285hp - PCM 1.23:1 Transmission
OJ XMP 4 Blade CNC 13x15.5RH
"People do weird things to boats" -Unknown