Help! No power on boost, backfires thru intake

[Aerotech]

I need Guru help here....

'91 EJ22t ran fine one day, crap the next, nothing touched. Symptoms include:
-Runs fine off boost, part-throttle, revs well, normal power.
-Blip throttle hard, engine spits up, even before turbo spool-up
-On boost engine has no power, spits up thru intake
-idle is ok until I encounter the problem, then is low/rough, occasional stalling

Checked all vac. lines, intake plumbing, all OK/in place
Same tank of gas it had for 3 days prior, no problems
Seems to be throttle-position dependant, not boost-related; I may be wrong there, but it only happens past 1/4 throttle, and happens immediately off-idle if I stab the pedal.
Does the ECU advance or retard the timing in relation to the throttle position? This feels like having your distributor turned too far.... or a fuel starvation problem. Clogged filter? But it ran just fine 8 hours ago....

Any help or suggestions are appreciated.

Thanks,

[THAWA]

How are your plugs and wires, dont have to worry bout the distributer crap, we dont have em

[vrg3]

Yeah, I'd check your plugs and wires first too.

Bad fuel in the tank can be the kind of thing that makes it run okay and then just all of a sudden run badly, especially if something suddenly clogged the sock or something like that.

Does the check engine light come on at all?

[DLC]

I'll third that ignition check. It also sounds like there could be a timing problem...