I drove the 617A motor a lot over the last few days. 1100 miles overall!

I posted before how I don't seem to have the power I used to have before all the big problems I had last year when I had to replace my inj. pump... except that power seemed to return to some degree on this trip, only it was on and off.

I would notice this odd bump in power sometimes and it was in the mid-upper RPM range when I was accelerating. It felt like another cylinder would suddenly start working... or as if a car had pushed on my bumper from behind. It was a good 15% bump in power and it was instant, not like a turbo bump which is smoother and takes a couple seconds. This was OFF and then ON. I have a boost gauge so I can watch the pressure and nothing was weird there. Didn't notice anything odd about the exhaust smoke (I barely have any no matter what I do)

TONS of recent service from my big break-down problem last year...
Fuel filters are basically new
Valves adjusted a week ago but were 95% in spec anyway
Diesel purge done recently
Was running my usual diesel additive
Throttle linkage checked
No leaks anywhere
New fuel lines and lift pump from last year
Just replaced manifold gasket
Turbo in exc. shape, had about 10lbs of pressure at max throttle
ALDA backed all the way out
New air filter

Out of ideas... other than maybe an injector has some weird issue? I doubt that though. Could the timing somehow change slightly, suddenly?