Having this same issue. Replaced the TPS and the Jeep (Grand Cherokee 1999 4.0L 6 Cyl) will die when I take my foot off the gas.

Question about this, I've never replaced the TPS before, and when I went to put it on, the piece that goes into the TPS didn't match up, so I had to tip the TPS a bit to get it to fit. Now I'm wondering if this is what is causing the issue. I tipped it only about 22.5 degrees Counter Clock Wise (facing the engine/cab)
Would this be the issue?

 

The Grand Cherokee group is over at https://www.cherokeeforum.com/f5/.

But to answer your question, it's possible the TPS isn't engaged properly and it's not turning with the throttle. If you have a voltmeter, I would measure the signal and make sure the output is changing as you move the throttle by hand with the key-on and engine off. It dhould go from ballpark 0.4 volts to 4.5 volts (don't remember the exact values at the moment). You wouldn't be the first person to get a defective brand new Chinese made TPS.

 

Thanks. I purchased the TPS from Rock Auto, it's by NTK. Not sure if it's chinese or not.
I have no idea how to check the voltage on it. There appear to be three connectors to I test across. And I'm going to guess I have to test across the connectors on the TPS somehow, and not the plug that goes into it, right?