93 4x4 22re power loss

My 93 yota had a blown headgasket, and a warped head, after it was put all back together with the new head and running, it seems to have lost alot of power, especially when going up hills, and when starting off from a red light, it backfires through the intake sometimes when I hit the gas. the timing seems to be set right, it has new plugs, cap, air filter is good. took off the cat and it was still good. im running out of things to try. any chance it could be a sensor? like an o2 sensor or something. any help is appreciated.. Thanx

Make sure the timing chain is not off by a tooth.

today the yota died on me in the middle of the woods. luckily a few people drove by who were getting some firewood who had the same prob with their 92 yota, it wouldnt start like it wasnt getting gas, the efi fuse kept blowing. turns out the o2 wiring fell onto the exhaust and melted and shorted out. i cut the whole thing off just to get home. the guy said it will prob run like crap w/out the o2 sensor, but it runs the same as it did b4 it died, just kinda cruddy going up hills and at low rpm. is it possible the o2 sensor was out the whole time and thats what caused it to run like that? im going to rewire the sensor tommorow after work, is there a way to see if the sensor is bad itself by testing?

I moved the timing chain back a tooth, it runs better, but still feels kind of weak. when we set the timing, we tried advancing it a little. That seemed to make it back to normal but it was pinging. any way to keep it advanced without it pinging?

my 89 has had similar problems. might want to check you throttle position sensor. If these are nonfunctional or improperly adjusted they can cause power loss and poor gas mileage