gas gauge and tranny problem

Alero 3.4 V6 - Two symptoms at once are occuring with this problem- about 20 seconds after starting the engine, everything starts out normal, then the gas gauge drops to empty, and stays there, and the rpms at idle go up to 1200 or 2000, and all the tranny gear shifts slam into gears. The rpm's stay high in drive (have to keep more pressure on the brake when stopped) and cruising rpms are higher, also. I have been told a ground connection is probably missing, but I need to know where to start looking. The car otherwise is running great, except for a high-pitched buzzing noise appearing to come from the fuel tank (pump?) but that had been present for a couple months before the new problem appeared. TAI.
Clearlize2001@aol.com

[Redog]

Don't know about the tranny but the gas sender may be "floating" Sinking to the bottom and rising back up giving the wrong reading.

Try disconnecting the battery for about 15 mintues and reconnect it. Maybe something has to be reset.

I've had similar problems with my Gas gauge as well. The first time the problem was occuring there was a resistor in the sensor which was shorting out and basically grounding the circuit which was causing the gauge to show empty and then maybe if I was lucky it would come back up. The second issue I was having was apparently caused (according to GM anyway) by a contaminant of some sort which was introduced into a gas pipeline which feeds the Toronto area. The contaminant was coating the sensor and causing messed up readings. So if I had 3/4 of a tank it might only be saying I had 1/2.
With the first problem I believe GM just replaced the resistor, the second time the tried some fuel additive to help remove the coating which didnt work, so they ended up replacing the gauge.

When GM acknolwedged the second issue they sent out Petro Canada gas cards for $20 of free gas along with the letter. The letter is also good for a free oil change.

The transmission is running at max line pressure due to some sort of electrical or sensor code that is setting. No that said, the code that has set my be a type B code which means you won't get a light and if you key off the code goes away.

Thanks to SC/Alero for helping me troubleshoot this. The fault turned out to be the TP Sensor. It was intermittant at first and the computer diagnostic indicated P1635(5 volt reference circuit out of tolerance), but the next code indicated was P0463(fuel level sensor high voltage), and that threw us off. Fortunately, the TPS finally failed entirely. What I would like to know is, why did it affect the transmission to that degree?
I should also mention that this car is running the supercharger originally from Springs fastest Alero's car (and doing great so far). I am running about 5-7 lbs. boost right now with CAI and water methanol injection, but the car is otherwise completely stock.