I power washed the engine, and now have what seems to be a ground problem. The gas gauge is eradicate, and it seems that the transmission is also.

There is a small voltage regulator on the back of the instrument cluster. Getting at it requires taking the dash apart. Not an easy job.

Transmission problems. Have the codes read. Most problems with this is internal transmission. Consider the cost and the vehicle.

You have a ground problem. Since it starts battery to engine ground is good. You need to check or add ground wires from the battery to the body, from the engine to body, and I put an extra ground wire from the transmission to the engine.

There are three fixes possible for the gas gauge....but I would have this troubleshot by a garage:

1. The gas gauge itself does not work anymore. It could have just finally "died". Problem is, you cannot replace just the gauge. It has to be the whole instrument cluster. Having a garage shoot power TO the gauge and then shot the gauge itself will let you know if the gauge assembly is bad.

2. The fuel sending unit is bad. This means the wiring to the gas tank fuel pump/sending unit is bad and does not work. The signal is not being sent to the fuel/gas gauge. This means the fuel pump assembly needs replacing.

3. There is a wire problem somewhere between the gas tank and the dash to the fuel gauge.

The transmission leaking but still reading full just means that there is plenty of transmission fluid in the transmission. The drips or spots you are finding are not enough to "read" low enough. Unless you have a HUGE spot of tranny fluid left on the ground, I would just think about a transmission fluid filter change. This way, a new pan gasket will be installed and fresh fluid filled to the proper level will be accomplished on your car.

If none of the gauges work, there is a power problem.
The gas tank sender grounds the fuel gauge and the temp sender on the engine block grounds the temp gauge.
Could be a wiring harness issue or a problem with the printed circuit board too.

There are three possibilities. The gauge could be defective. The instrument panel voltage regulator could be bad or not grounded or (most expensive) it might be the sending unit.

could be a lose ground somewhere. check the wires from your batery and alternator. specifically the grounds. no ground no power.

the buffer plates in the tank seem to be loosely held! so sometimes they fall on the sender unit,causing the gauge to drop!!!!! when the vehicle is shaken!!!! remove that tank and have the plates checked!!!!

It sounds like a ground wire was left unhooked.

I think the firstr thing you should do is check for loose ground wires, and wires that are being pinched. Check your battery cables for tightness on both ends. It seems like something is shorting out when your engine tips when you put it in gear. Check all the wires that are anywhere near the transmission. Good luck.