Running issues after sitting for awhile.

This is my first post. I've searching on all of these forums for help with my taco.
Okay I had my engine replaced with a used 2rz. My old 2rz I killed it. Now when I first got it replaced it would die when I let the RPMs get to high and put in the clutch.
Now I'm not having that issue, when it sits for awhile and cools off it will start, idle for a bit, then cut off. If I start it and get on the gas to warm it up some it'll idle fine. Could it be the fuel injectors? Since the engine wasn't in use for 6 months until it was swapped into my truck.
I took apart the throttle body cleaned everything up & cleaned IAC valve. No Check engine light. Maybe a fuel issue.
Thanks for any help.

 

Could be a few things, maybe MAF sensor is bad, maybe TPS (P0120) when you took off throttle body did you replace that thin flimsy metal gasket ? It's a one shot deal meaning once it's loosened/removed the sealing integrity is gone & needs to be replaced, possibly fuel filter if not enough static line pressure or flucuations... I'd scan it for codes regardless if no CEL present..

 

I should add that if you aren't sure of the engines history (one you bought) something else to consider..