Turbo 400 question

[dtkarst]

Got a 71 Longhorn BB with factory 400 pickup I've had for awhile that I've decided to tinker with a little. Runs and will drive, but not normal. I shift in reverse and it kicks backwards/engages like it should, then i shift to D and it doesn't kick in and engage like reverse does. I give it gas and i will slowly creep forward most of the time sometimes it doesn't. Doesn't make any abnormal noises, just won't move. I can then shift into L1 and L2 and it'll engage and drive like normal. Possibility that it could need gone through, not sure. I crawled under it and found the vacuum line is hooked up, but on the driver side, there are two wires (a black and an orange) with just the orange wire hooked up. I only see one prong on the switch..my question is, shouldn't there be two prongs on it? or is there a male end and a female end on it? Its been blizzarding all morning so i can't get a for sure look. But both connectors on the wires are female end. Could that be the issue I have? The oil is still clean and doesn't smell burnt. If i need to replace it thats what ill need to do but I'm just trying to exercise all options before i change it. thanks