The gas gauge has power to it when i start the vehicle it goes to full and stays there for some time. After driving for a while and stoping and letting the car sit at idel the gauge begins to bounce

Check your oil level

sounds like you may have a bad fuel level sender problem. as for the check engine light coming on and storing a fault code that is a separate issue.

It has 2 possible solutions 1) fuel sending unit is going bad which the tank has to be dropped to change, 2) you have a bad cluster panel. Hope this helps

This is my drive cycle a generic drive cycle i have used many times over the years and it has never failed me most drive cycles are too specific and impossible to adhere to for most drivers follow these steps exactly 1. make sure all codes are cleared and no check engine light is on 2 make sure the fuel level is between 1/4 and 3/4 full (this is part of the enable criteria for the evap monitor to run ) 3 let vehicle set overnight 4 start engine and let idle until the temp gauge is in the middle (this cold start enables the evap monitor and runs the O2 sensor heater test )5 drive vehicle around town avoid the highway stay at below 50 mph and when stoping at lights remove your foot from the gas and coast from around 50 to about 10mph or less if possible this will run the EGR monitor after about 3 to five miles of this proceed to the highway or freeway and travel over 50 but under 70 mph for about 3 to 5 miles this will run the catalyst test provided the O2 monitors passed if they didnt you will have a check engine light on before this point also i do a coast down on exit ramps (no braking) they make great places to get that EGR to run ONCE YOU START THIS PROCEDURE DO NOT KILL THE ENGINE OR SOME OF THE TEST WILL FAIL TO RUN

is it a such thing as a floater tank being on the montana van

Could be a short to ground on the positive wire leading from the fuel sender.

new sender unit required

Do the doors unlock when you shut the key off? Also unhook the purple wire to the sending unit in the tank, Gauge should read empty. Ground the purple wire, it should read past full. If it works this way, replace the sending unit in the tank.

yes it the fuel pump . the float is getting stuck

Either fuel sensor is bad or coated with sulfur residue from inferior gas. Try a can of Sea Foam gas treatment OR can of Techuron concentrate. Both available at auto parts and , of course, Walmart ! Add to full gas tank, drive 75 - 100 miles and see if all is well. If not, condide4 sensor change