RPM goes up and down and car runs bad when EGR temp sensor is plugged in

Thanks for your fast reply, I'm going to check the gaskets right now. I already replaced the hose to the map. But could it also be a fuel pump problem or fuel injection problem. I want to be sure before I start buying and installing these.

Yesterday I took out the TBI, the wires were fine but the gasket looked a bit bad, so I use liquid gasket (silicon seal). I live on a remote island, we do have a NAPA deal but the gasket is not in stock and takes 2 weeks to get here. This morning the cars runs fine and the check engine light is not burning. BUT every time I seem to have found the problem the car runs fine and starts running bad within a day. Keeping my fingers crossed it was a gasket problem.
I don't have the gear to check the fuel pressure, but if that would be the problem I would think it would run bad all the time. And my cars runs perfectly fine this morning, even with the EGR sensor plugged.
Before this morning, when I unplug the EGR sensor, rpm goes up and the car runs a lot better
Really appreciating your input here, been having this problem for a few months and your info finally makes some sense!

Hey hmac300,
Hope you're still following this thread! I removed the silicone sealer and replaced the gasket. But still when the car runs stationary the rpm goes up and down, not smooth at all. I measured the fuel pump pressure and it is only 2 psi. So probably there lies the problem. I can put in a new fuel pump but I measured another problem. On the wire from the engine to the fuel pump I only get 8 volt instead of 12v. If I change the fuel pump I still have this problem. My question: is it a problem that I only measure 8v and what could cause that low voltage?

Thanks again for your help!