5.0_GT

Got my 88 5.0 running great went to the track put downa couple of 14.7s with just headers and wires everything else stock, the last run when i had problems, car just bogged half way down the track and ran 15.8, then it woudnt let me go wot at all just die and back fire when i punched it, so went and parked it let it sit for about 30 minutes or so, we left, car ran great felt like it lost a little power, but not to much, then next day headed to work didnt get 10 feet car just died and woudnt start, eventually started then went to work, left work i would go about 1/4 throttle the engine would cut in and out bucking and back fireing, then this is kinda weired i would cruise in 4th, then i would punch it i wouldnt even move then couple seconds later it would pick up and go, it would do that in all gears, 5-speed car, then brought it home pulled codes, just key on got 31,67, then first engine run test got 46 and 31 then the next engine run was 46.31,41 and 91, iam confused, any thoughts