1995 chevy s-10 2.2

I bought it a couple weeks ago for a project truck but it ran pretty well at the time. a week after i bought it i decided to just drive it daily since my other truck got horrible gas mileage. first morning i drove it i was going down the road and it began to sputter and die on me. once i got it started again it ran absolutely fine up until i got to operating temperature then it sputtered and died again. i decided to change the spark plugs, oil, oil and air filters and spark plug wires too just to make sure that wasnt the problem. when i got under the hood i noticed the mass air flow sensor was unplugged so i plugged it back in and disconnected the battery for 10 minutes to reset the ECM. after i finished all that i started it up to see if it would run, it did for about 5 minutes. i got it back going and it warmed up to operating temperature and like clockwork is sputtered out and died.
Yesterday i replaced the fuel pump, strainer, filter and wiring harness in the gas tank. still the same symptoms. i swapped out the relay last night with a new one i picked up and that didnt do anything this morning. i also got the temp switch and temp sensor last night. one of them i believe the switch (near the thermostat if anyone could clear that up i'd appreciate it) and still the same symptoms. i cant find where the other one goes to save my life right now.
does anyone have any idea what could cause the problems my truck is having?

its much cheaper to test things than just buy a ton of parts hoping it fixes it.
getting any check engine lights?
will it start right back up after it sputters out?

there could be a reason someone unplugged a sensor, might want to follow the main harness and check to see if anything else is unplugged, there are a ton of sensors.

i took it to get it tested and the only code it was sending was a fuel pump code so i replaced it and the wiring harness. im at a complete loss now. it will start after you let it sit for a minute. and its has no check engine light on thanks for the reply