'94 w/ air temp sensor and TPS problems

I have a '94 bonneville with some really odd problems. First it gets horrible gas milage all of a sudden. I'm talking barely 200 miles to 16 gallons of gas (you do the math). Not only that but it idles erratically. I have had it idle as far up as 3k and as far down as 600 rpms. Check engine light come on and I had it read.

Car has a rebuilt motor and transmission. Motor was done at 90k and tranny done at 132k.

The culprits? The Manifold Ar temp Sensor along with the Throttle Position sensor. Now the TP sensor I just replaced about three weeks ago. And I put another one in before that one exactly one year ago. So here are my questions.

Why is it eating TP sensors? Also where is the Manifold air temp sensor?

I do all the regular maintence on the vehicle. So I know it's not the fuel filter as I did that back in November. Also the fuel pump is working just fine.

If your talkin about intake air sensor it is usually in your air filter box or the tube going to it.Also TPS may not be your problem,a maf sensor can do that to your idle also.If you search TPS there is a way of checking it with a multi meter.Was TPS installed properly.