F150 Odometer/transmission/lights problem

Truck: 1994 F150 XLT w/ Automatic transmission

After sitting for several months under a fir tree, I pressure washed the truck to get the acidic tree debris off, including around the edge under the front trunk lid. I tried to not spray the back of the front dash. After discovering the wiper blades were toast, I went to drive to get some and found several problems…1) the speedometer/odometer quit, 2) the truck lurches between “gears” when it automatically shifts (worst for 1st shift, lesser at upper shifts), 3) the cab lights no longer work. Since I know some statistics, it seems highly improbable to me that all 3 things went wrong at the same time for independent reasons, so I was thinking blown FUSE. I opened up the fuses and found 2 that listed cab lights, transmission, etc. They are both little aluminum box kind of fuses (I don’t know what you call them). I tested continuity with my VOM and they are OK, I think. My brother says there may be a cable loose that connects to odometer and is used by the transmission when shifting…

Any details, suggestions, or instructions on how to check the cable appreciated, since it’s up for re-registration and I don’t want to have to take it in for service if I don’t have to.

Saw another discussion about a Bronco with a similar problem and they talked about a faulty Vehicle Speed Sensor…Is that something I would want to try to replace myself? About how much are they? I have a Chilton’s but working single mom - no time or money! Don’t want to waste all day on it, but can do it if it’s quick and relatively easy and saves $$.

Thanks!