Sr20det rich at idle then lean with throttle.. please help

[Cubantunr]

Ok so here's the deal Sr20det redtop s13 hatch. At idle the car runs ok then after about 15 seconds it starts to get very rich and stays that way, I went to give it a little gas and Bam just straight to lean and almost dies. I barely touch the throttle and it jumps from rich to lean, let off gas and back to rich. Stock injectors, nismo fpr. The o rings were bad so I replaced them, set the fpr to 36 idle and 42 with vacuum hose disconnected, the injectors were checked and ultrasonic cleaned all tested good but that doesn't mean they're spraying consistent does it? Checked them with the ohm meter on a cold night and read back 10.7-11 on all 4. Replaced pcv valve and all still the same. The injectors sat with bad gas for about a year before the cleaning. Idk what else it could be. Any help appreciated, thanks.
Btw I'm running walbro 255 fuel pump.