sbdye88

I just bought a 1990 4Runner and it start up great with no issues on a cold start. However if it gets driven for about 20 to 30 minutes or longer the engine will have a low RPM idle sometimes less then 500 and will stall at a stoplight. It will also shut off on a warm start and I have to rev the engine to keep it from stalling. For instance I drive to the store, shut the engine off then come back and turn the engine on it will shut off after a few seconds, to get it to stay on I have to rev the engine. I have also noticed the oil pressure gauge shows it has low oil pressure during this same time, perfect oil pressure until the engine has been running for 10-15 minutes. No low oil pressure warning light however. Can anyone lead me to the right direction to fix this?