I have a 2005 Monte Carlo SS and for the last month I have been having issues with it stalling out, it doesnt matter if it's at a stop or when im accelerating it just stalls out, it has a check engine light P0446 & this is what I have done so far:

Fuel pump,spark plugs & wires, checked all fuses, Iac valve, charcol canister, purge valve, purge valve on top of throttle body, fuel pressure sensor, checked all evap hoses, checked fuel line, alternator, gas cap & had CAT checked & was still good.

Once I do somthing to the car it runs great for a couple days and then check engine light comes on and it stalls & starts back up. Also not sure if this has anything to do with it but gas, oil & psi boost gauges dont work at all.

Any opinons will be appreciated. Thanks!