Went to jeep show and washed off outside of jeep with pressure washer at car wash. Ever since, my battery gauge shows lowest reading and jeep barely starts. I'm thinking I got water into the motor area. If so what can I do ?

 

Have the battery load tested and the alternator bench tested. Any parts store will check them for free.

 

It won't run unless I floor the gas. Once I let off it dies !

 

Check all of your grounding points and make sure that they are clean. One bad ground can cause a lot of strange problems.

 

how old is the battery?
get all the mud out of the alternator?

if you can't get it to the parts store, do you have a battery charger? will it hold a charge?
if you have a multimeter, you can check the alternator output voltage while it's running

 

do this ^^^^

That's symptomatic of the alternator putting a ton of drag on the system or the battery being weak.