Dyno says 113HP, belt gets thrown off, what say ye?

[Ron]

WRT alignment? That is alignment of the pulleys for the water pump / alternator, right?

Yes.

Yeah, It starts instantly and dies immediately unless I keep it at 3-4000 rpms.

It starting instantly indicates the charging system-battery is probably OK.

No, I think my engine runs ruff at low rpms, but runs smoother and smoother the faster I'm going. Kind of like the engine always sounds like its close to stuttering and sputtering out at idle / manoeuvring speeds, but the fast it goes, the less engine noise I get and the less vibration.

Sounds like cylinder(s) not firing/missing. You might try pulling plug wires one at a time while it is idling and listen for any that do not change the sound of the engine.
A good test to perform while it is forcing you to hold it at high idle to keep it running too.

Please elaborate a little, "check pressure at the plate", what plate where?

The air metering plate (where the air cleaner/breather leads to)....If it dies and you immediately switch it off, no resistance when you press down on the plate would indicate a a loss of fuel pressure (bad filter, pump, restriction, etc).

[Bitsyncmaster]

The A/C compressor cycling on couldn't possibly draw enough power to strangle the fuel pump, could it?

Would not think so. But with the AC on your cooling fans are running which are a high current draw. Just do a voltage test at the fuel pump with the AC on to test that condition.

[DrWin]

Yes.

It starting instantly indicates the charging system-battery is probably OK.

Sounds like cylinder(s) not firing/missing. You might try pulling plug wires one at a time while it is idling and listen for any that do not change the sound of the engine.
A good test to perform while it is forcing you to hold it at high idle to keep it running too.

The air metering plate (where the air cleaner/breather leads to)....If it dies and you immediately switch it off, no resistance when you press down on the plate would indicate a a loss of fuel pressure (bad filter, pump, restriction, etc).

Roger. I'll have to look for that, both the pressure at the plate and the non-firing cylinders.

[DrWin]

Would not think so. But with the AC on your cooling fans are running which are a high current draw. Just do a voltage test at the fuel pump with the AC on to test that condition.

Right, that should be easy to test. Thanks.