1999 Ford F-150 Speedometer showing > double actual speed.

So yesterday was the first snow in the area driving to work I go up an alley to the parking garage. It's a single lane uphill. Someone was backing out of their driveway and I had to stop on the incline. It was icy and when I tried to start moving my tires were just spinning from lack of traction. I'm very slowly creeping up the incline another car behind me is waiting. So i'm like I can't get my truck moving let me switch on the 4 wheel drive. I let off the gas turn on the 4wd and press on the gas again. The 4wd is a little hesitant to kick on but it did and I get moving. The engine is seemly off slightly no at the appropriate rpm and my speedometer is showing me going like 30-40 mph when i'm creeping like 10mph. I pull right into the garage and park and think huh that's kinda weird. After work I go out to the garage and speed it still showing really high on my way out the garage. The garage exit right onto the highway ramp and I try to get going but the engine stutters and the speedometer is pinned. I'm doing around 40ish mph per my gps. I think this is the engine governor. So I get off the highway and limp the truck home. From what I've been reading I think it may be a speed sensor. Can someone confirm or give me some other ideas.