Where is coolant temp sensor on 1988 Cutlass cierra 2.8 MPFI

I have a 1988 Oldsmobile Cutlass Cierra with a V6 2.8 litre multi-port fuel injected engine, W-series. The car has power steering and power brakes and air conditioning. I can't find the coolant sensor. Can you tell me where it is? It is not at the water pump outlet.

The car has 261,384 Kms. The temperature gauge in the dashboard panel always reads the same 40 degrees C. I can tell when the engine is hot by the drop in oil pressure from ~550 to ~280. The car has very low gas mileage. The engine (or transmission?) Shudders after 5 or 10 minutes of driving, except when coasting or in 2nd gear or at speeds over 110 km/hr. I accelerate to as fast as I can go and then coast, and repeat. The transmission often bangs into gear when it dwnshifts to 2nd. The center constricted band of the catalytic converter glows cherry red.

I am guessing the computer always thinks the engine is cold, and feeds extra fuel, which the converter has to burn.

It will cost me $76 to have the error codes scanned, $76 for a new temperature sender, and $36 for a new temperature sensor. Is there a sender on my car as well as a sensor? If so, also where is it? There is no sender mentioned in the engine wiring diagram.

How can one test a sensor to see if it is good? With a digital multi-meter?

Thanks for your help. I would send you a donation, but I have no credit card.

:)

my e-mail is bobhinton8st@yahoo. Ca