I assume, when you say air locking, you mean the filling station pump handle is shutting off every few seconds if you don't pump excruciatingly slowly.
That's a symptom of EVAP plumbing issues. Vent valve, the EVAP canister (I've seen it called a fuel vapor canister, charcoal canister, vapor canister and a couple other names ), hoses connecting the filler neck to the EVAP canister and tank, hoses connecting the vent valve to the EVAP canister, and even spiders or mud daubers making nests in the Vent valve intake.
The fuel gauge could be several things. You'll need to test it and inspect things to find out what's happening.
1-The wiring between the fuel-pump/sender module and the fuel gauge can get damaged or one of the connections can leak and corrode.
2- The fuel level sender can fail. The sender is essentially a rheostat (high amperage potentiometer or variable resistor). The wiper of the rheostat is attached to a small diameter stiff steel rod with a float on the end. Eventually the rheostat in the sender can wear out. Unfortunately it's a cartridge that contains the level sender, fuel pump, and the EVAP system fuel tank pressure sensor so the sender isn't cheap. If you're keeping the car get an OEM part. Aftermarket fuel pressure sensors, fuel pumps, and senders have issues. If you've replaced the OEM General Motors fuel pump module with an aftermarket part then the aftermarket sender is suspect.
3-The fuel gauge stepper motor that drives the fuel gauge needle in the instrument cluster can fail. Stepper motor failures are common on GM vehicles between 2000 & 2010 or so.
4-The instrument panel has No-Lead solder on the circuit board to comply with international RHOS regulations. This solder will crack after multiple thousands of hot-cold cycles making intermittent and open connections to the surface mount resistors, the harness jack, and various other components on the instrument panel. It's a common failure on instrument panels, electronic rearview mirrors, heater controls, BOSE amplifiers, and Delco radios made between roughly 1999 & 2014. I've fixed dozens. You need QUALITY 60:40 TIN:Lead rosin core solder (Kester), an inspection/rework microscope (these surface mount parts and defects are tiny) these start at $300 for barely useable, and a decent quality temperature controlled soldering iron (expect to spend at least $100 for a decent Iron). The circuit boards are very thin so thermal control is exceptionally important. If you overheat the PC board it's exponentially more difficult to repair it. The fiberglass layers can and will delaminate and the copper traces will lift off the board. As tempting as it is... that 25W and 40W Weller soldering iron at WalMart will damage the boards.
Change the fule pump and be over with it. And clean the E-VAP hoses while you are down there. Save yourself a headache looking for it. Change it, it comes with everything you need. A better quality one dose. Good Luck. That will do it.