22re misfire?!?!

I have a 94 toyota pick up with 22re engine. Was rebuilt a little bit ago before i bought it. Anyway noticed a small misfire but it drives completely fine. so i changed plugs and wires..distributor cap is less than 6 months old. Any ideas? Only codes that are thrown are 21 and 41..o2 and tp sensor.

 

I would start with the TPS and the O2 then. Check the settings on the TPS w/ a Ohm Meter.
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

 

If you get everything within spec and the miss is still there. Give this a read and do what it says.
http://22reperformance.com/faqs/dianostic-info.html

 

I had a 1998 with the 22RE. Unscrew the idle speed screw. Like post #3. You'll see an "O" ring. Go to the hardware store and replace it. I changed mine and it idled smoother. This "O" ring is only in contact with air so doesn't have to be fuel grade.

 

So i put the TPS on and adjusted timing and had it idleing at 750 per the info plate under hood..went to give it gas and nothing except a sputtering sounds, not enough fuel or air? Brought it to around 1250 rpm and was able to throttle it pretty good. The thing that is confusing me now is that it will backfire when in the 2k rpm range but WILL NOT backfire if the throttle is all the way open. Not sure what to check next. Anyhelp will be appreciate