TPS Drama! All out of ideas

So I'm getting around to fixing up the '89 ~ looking at a 2 door a friend has - and I finally believe I know what the random no start issues are caused by.
Mostly because I've thrown $$$ at everything else!

Seriously, I've discovered that the TPS doesn't stay set to spec.
I followed 89Lorado's instructions for setting the TPS for a manual.
I get it to the perfect sweet spot...
And as I tighten the screws, it jumps from .83 back to 4.53+
No the tps isn't moving.
I've tweaked and played and as long as I don't tighten it too much it stays at .83

But then, after a short trip (20-30 min), I can cut the engine and it's off again.
My guess is the engine vibration and temp enable it to move???
Don't know, but going crazy.

It's a new ECU and a new TPS. I thoroughly cleaned the throttle body...
Out of ideas

I feel for ya, but adjustable TPS, all my knowledge is 98+ Off the top of my head I'd say the TPS is bad, unless you've tried two and they both do the same thing. Being able to measure the voltage and seeing the issue should put you well on to finding the cause and the cure though.

I would suspect the new TPS is not what it is supposed to be. I have had bad sensors out of the box too, to it is possible it is bad. Most of them made in China nowadays and quality control is poor

It's from O'Reillys
And there's a lifetime on it
I'll pick up another the weekend.

Thks guys

this is why i pay the extra dollar for a dealer electrical part not aftermarket. and also look at the mating surface if there is any dirt where the tps mounts to.