03 F225 idles fine then stalls under load

[bbqsdm]

Engine had new power head and will only idle. At power in gear it backfires, loses power and stalls.
I ran Yamaha diagnostics. The intake manifold pressure sensor was out. I borrowed one from another motor.
The computer showed engine temp at a max of 150F after 45 minutes of running in neutral
All codes were cleared and we took off. On powering up it started backfiring and stalled again.
A recheck of the program found no codes.
A message told me to put the motor in neutral or turn off the motor when I tried engine off tests on fuel injectors.
Can a bad neutral switch be the problem?
The fuel rail showed 45psi.

[boats.net]

Sounds like it's out of time, check belt timing.

[bbqsdm]

I will check timing with a light.

What about a bad neutral switch? Does it cause ongoing problems?

[boats.net]

Check the timing on camshaft to crankshaft to make sure camshafts are in time, timing light wont work for that.