Pat,
I know Mark knows what he is doing, but to be honest with you I don't understand his advice. If you had a fuel system problem, the pressure would drop off or at the least become unstable. Plumbing a return hose back to the tank will not help.

As far as the injectors losing power, why not just use a DVOM to monitor it, instead of trying to rig an alternate power supply?

Start looking very hard at the ignition side. I will ship your ECM tomorrow, if you want I will also include a spark tester so you can confirm/rule out loss of ignition. BTW, has the ECM ever been reprogammed? Are you sure the rev limit is properly set? The way you can tell (with a scan tool) if you are hitting the rev limit, is to watch the Fuel Rate. When you hit the rev limit it will go to 0 GPH.

when it come to ignitions I would not run anything MSD has, now they have been bought out most of their componants come from china=junk, just pulled all their stuff off my top sportsman race car, my thoughts...MSD may soon die...totally useless...matter of fact I pulled a 7al2 box, pro-billet dist, and replaced with a couple year old mallory unilite that i ran in my checkmate...picked up .500 over what it had ever run with the msd stuff, and they had all the suff back and went thru it this season....Rob

Thank you Dave for checking out my original ECM. Yes, please do send along a spark tester. I think I should test the most basic things.

The feedback I've been giving Mark is that is appears to be fuel related. Everyone that has ridden with me says that the engine sounds like it is starving for fuel.
It could vary well be ignition though; those were the original error codes.

I do believe the ECM I'm using has been reprogrammed with the stock calibration for my engine. No, I don't believe it's hitting the rev limiter because I can trim up and get the thing to rev 44-4600rpm. It's the last 20% of throttle that makes the engine crap out.

This may sound completely off-the-wall, but have you looked at the pick-up tubes in the fuel tanks to look for cracked tube/obstructed pickup filter?

Nope, but it is on the to do list...

I have been chasing possible electrical problems because I have had 3 different ECMs on the engine reporting different faults.

I have checked the wiring pin to pin more than once. I have also checked the grounds.
I think the first thing I'm going to do before I go for another ride is tie in another ground to the pin/wire in the connector to the ECM.

I run a MEFI 1 and it recently went into continuous knock with a second alarm, IC bypass ckt grounded or open.

This sounds like a common result of a failed ECU.

On MSD; I've run their stuff for 20yrs in my drag cars and never had an issue with any of it.
They've got a MEFI4 system for about $1200 that I wouldn't mind trying.