my truck did that. here was my problem: the cable that goes to the top latch from the lever inside the door, has a small i guess its called a notch that it kinda presses laterally into the latch. the lower peice of that was broken (little cheap plastic). i was able to ziptie it to the door latch and has worked great. just cuz im cheap though. but the panel has to come off for all that.
1997 f-150 super cab 4x4 4.6, cranked t-bars, k&n CAI, hypertech tuner, gutted rear cats, flowmaster with duals, 7 inch flipscreen with 10in sub and 2000 watt amp, swapped 98+ 4r70w.