Codes: P0463 & P0545

Need some guidance. I know that the code P0545 is the Compressure Clutch Control Relay, autozone part number MT0225, $12.99. And code P0463 is the Fuel Level Sensor. I cannot find that damn part any where, is it a dealer part? And also, how do i replace it? Drop the tank? The truck is running rough as hell, it misses, stumbles at idle and has a slight miss while accelearating. I took it to AUTOZONE and that is the only two codes it pulled. I am not sure that these two codes would cause it to run badly. The Fuel level code i can live with, every ounce in a while when i turn the key on, the fuel level doesnt register, i turn the key off and then back on, everything is fine. And the the slip that autozone gave me explaining CODE P0545 is: "The PCM has determined that the voltage signal from the exhuast gas temperture sensor in bank 1 is too low for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while Bank 2 identifies the cylinders on the oppitsite bank)."
What the hell does that mean? I thought P0545 was the Compressor Clutch Control Relay? Need help, confused as hell.

Anyone? I have decided to change the AC Compressor Clutch Relay and the Pre-Cat O2 Sensor. That will clear the codes, but if they dont make the truck run better, i will have clear codes, and i will have new parts on the truck i wont have to replace for awhile. I am also ordering a FASTMAN O2 SIMM because im taking the cat and the mufflers off to run strait pipe. I want to replace the pre-cat O2 Sensor because i want to keep my fuel-air ratio's correct.

I know the fuel pump also controls the fuel gauges in some vehicles, perhaps that's where the fuel level sensor is located. I can't say for sure if that's the case with a Dakota, but that could explain why you can't find the part.

email me at macdonaldrp@yahoo.ca and i will send you the shop manual PDF. Fuel sending unit its fully explained with diagrams on p. 14-5 thru 14-7