1996 Land Rover Discovery please help Rover having issues

I have a 1996 land rover discovery that im having trouble with ok ill start driving it and it will run fine as I drive for a while it starts to act like its going to stall I can press the gas and it doesnt change when it does stall it wont start back up but if I go and bleeder on the fuel rail it will be nothing but hot air coming out until the fuel pump times out then I flip the key again and more hot air folowed by fuel then usually in a few minutes it will start and run for a bit longer, I had it checked for trouble codes and it only came back as a generic code about missfire and something about fuel managment, but they didnt have anything other than that im lost im not sure if fuel pumps quiting the purge line is blocked or tps sensor, thats another thing it have replaced plugs wires fuel filter air filter, any help is greatly apprieciated