Dieseling EFI engine

My vehicle does not switch off straight away and I have to stall the engine to turn it off. After I turn the key to off the engine does a slow lope until it is stall by me. I have no check engine light and an obd11 scanner finds no fault. The engine idles fast, 1250 rpm, uses a lot of fuel and shifts (manual) stiffly with revs staying very high between shifts.

At times I hear a loud bang and when I turn off the car I hear a crackling sound. I thought at first it was a hot muffler cooling after fuel catching but have since discovered massive vacuum in my fuel tank so much so it split the tank at the top! I have replaced the fuel cap but it has not changed. When I release the cap a great whooshing sound starts as air enters the tank.

At first I was told the dieseling was sensor related so all sensors have been replaced, IAC, TPS, MAF, new injectors, spark plugs, PCV valve, fuel regulator. Could this be an EVAP issue? Purge valve? Blocked carbon canister? Perhaps two separate issues? All mechanics I talk to say its impossible for an EFI engine to run on. But it does! After each 'fix' the car seems to run great for two to four days then goes back to its issues. Unleaded fuel seems to make it worse than e10.

Car has actually done 155,000 miles.

Please help. I am at my wits end!