Loss of power when warm

I have a 1992 4runner with 254K miles, automatic tranny, 2WD. Has been pretty reliable the past 4 years and I would like to keep the thing around. It burns about 1 qt of oil every 1000 miles but doesn't smoke.

My problem only occurs when I have been running for at least 20 minutes but sometimes not at all. Sometimes when I hit the throttle to overtake someone the engine will loose power or hesitate. Normally what happens is the engine starts to loose power no matter how much gas I give. If left alone the RPM's will drop to idle, regardless of the throttle position. I have found that putting the car in N and turning it off then starting it right back up again will get the power back if only for a few more minutes. If I turn it off for 5-10 minutes then start it back up it will usually behave normally for 5-30 minutes. It only seems to do this when it is warm. I have driven it 1-2 hours with no problems somedays and others I barely get 10-15 miles down the road when it happens. In stop and go traffic I just turn it off at lights if it starts acting up.

Any suggestions?

check cap, rotor, wires, plugs, and fuel filter to start and if that dont work take somewhere to put on scanner

Not sure yet but have replaced cap, rotor, wires, coil, and plug. Of course now the thing just got out of the shop because it wouldn't hold an idle. But they did clean the injectors and fix two vacuum leaks so I am hoping that will fix the problems