Loss of power happened in 2 stages -

Step 1: Partial loss of power, as if no wide-open-throttle enrichment. Leisurely acceleration. This lasted 1-2 days, under 50 miles. Start & idle OK, engine could rev to redline in lower gears.

Step 2: Power reduced to “limp home” mode while accelerating from a stop. Idle is unsteady; rapid full-throttle will nearly stall engine. Won’t rev past 3000. If full throttle is maintained, revs cycle between about 2300 and 3000.

NO Check Engine light (yes, the dash lamp is good.)

Background:
• Recent tune (within 2000 miles); new cap, rotor, ignition wires, plugs, flame trap, air filter, fuel pressure regulator
• Timing belt close to 50K

Checks performed:
• Fuel filter replaced (no change)
• Fuel pump relay swapped with known good unit (no change)
• All fuses and contacts checked
• Fuel pumps make appropriate sounds; car will start poorly if in-tank pump power is cut; car will die if power to main pump is cut.
• AMM swapped with new unit (no change)
• 1-1-1 codes on dignostic plugs 2 and 6 (but disconnecting battery while cleaning fuse block may have cleared codes)
• Inlet snorkel checked for leaks; none found
• No other apparent vacuum leaks
• Plugs look normal
• Air filter box checked for obstructions (none found)
• Throttle position switch replaced, throttle body cleaned.

Can't completely rule out a plugged cat, but I have no way to test that at home. Based on recent good running and a lack of any rattle from the cat, I think this is down on the list or possibilities.

I have not yet checked the coil... obviously it's not dead, but... not sure how to check it. The 'power stage' condition to the best of my knowledge is a binary thing - it works or it doesn't.

At this point I'm torn between searching for a reliable independent shop in my new home (Phoenix area - NO idea where to look) or throwing parts at it. Not even sure what parts I'd throw! Hoping to hell it's not the pricey, rare ECU.

Any thoughts?