Shutting off

I recently had my car put in the shop, because I was told that my transmission was going out the last time that I went and had my car serviced.
I was driving a few days ago and my car kept slowly shutting off, and felt almost like it was overheating. I had to stop and wait minutes before driving again out of fear that I might gt blown up in my car.

I wanted to know if anyone could tell me what is happening with my car, what steps I need to take.

Things to know:
I recently replaced the engine
Got the transmission looked at
Oil change is current
Its a 2006 Chevy Trailblazer

I'm really thinking about just giving up on it, and I don't want to if there's still a lot of potential left in it.

 

I had that happen to me in my little Mazda pickup many years back. It would drive along perfectly fine, and then kind of act like it was out of gas, and die. I would pull over when it started gasping and stalling, and then let it sit there for 10 minutes or so, and eventually it would start up again, and run fine. I never knew when it would do it, and it kept getting worse. Going up hills seemed to be especially bad.

I had people tell me all kinds of things might be wrong with the engine, but it actually turned out to be something really simple. My fuel filter was plugging up. After it sat a while, the sediment want back down to the bottom, so the truck would run fine again.
The fuel filter was an inline one, and was even pretty easy for my ex-husband to change; and once he did that; the truck ran perfectly again.

Yours might be something more serious, but a fuel filter is usually pretty cheap, and worth at least trying before you give up and sell the car.