RPMs drop while driving

[colecole2020]

im very confused on why my trailblazers RPMs drop below 1000 while driving . other then that she drives smooth.. but another issue arose after i took it in to be fixed never really did find out that reason on why she didnt work all those months but anyways when i go to fill my car up it lets me get a couple gallons in an then it starts acting like its full so then i have to wait a few mins an try it again so it ends up taking me almost a half hour to finally fill my tank up.. it was never like that til i got it back from the mechanic

 

[mrrsm]

For Diagnosing the cause of the "NO Fuel without Cut Off Issue", this is the BEST Video explaining How to R&R the Evap Vent Solenoid presenting with a P0455 Code showing up on an inexpensive OBD2 Code Reader:

Other possible areas to explore that are non-destructive or expensive, parts-wise include:

(1) Replacing a Dirty Air Filter.

(2) Clean out a Dirty MAF (Mass Air Flow) Sensor...Use ONLY CRC MAF Spray Solvent:



(3) Performing an Off The Vehicle Solvent Cleaning of the Throttle Body as per @MAY03LT ‘s Video:

For Diagnosing the Reduced Engine Power problem:

(4) Possible problems with the ACC Pedal (Accelerator Pedal = Gas Pedal) using an OBD2 Code Reader involve looking for the P2123 and P2128 Codes indicating the ACC Pedal HI & Low PCM 0-7 Volts DC Class 2 Network Position Signals are not working and the ACC Pedal should be replaced. Please Do NOT replace the ACC Pedal Module Assembly without first confirming that you have either one or both of these Codes.

 

[Mooseman]

For the clicking off while fuelling,
Filling with fuel always make the pump click off