Just got the car and started really digging in. Took care of a lot of touch up and tune up stuff first weekend with it, just today I went to go pickup a new kenwood for it and filled up with 93 supreme as I've been and as the previous owner had, and took it through the gentle cycle car wash. Touch free. Got out, thing ran like junk. Running real low. So I parked it and dropped it in park wondering if it didn't grab the gear or something, and it idled low and I shut it off asap. Here's what I've come up with (probably way off)
So the battery is too big, the last kid threw the wrong size Walmart battery in there and it doesn't sit right. Did get some water in the battery compartment under those panels in the trunk. I assumed it could have easily gotten water in the ignition. Possibly a shortage as well? Also read that it could be the COP? It does get reps when I turn the key. Ignites a bit and tries to turn, gets about 200-400 rpms then drops on me. Supercharger is attached to the best of what I can tell at the gas station it's still at. Waiting for my buddy and his trailer now and then we'll get it jacked up and see if we can better diagnose, but he's not a euro guy typically and never worked on a jag. Would like an experienced opinion and possible solutions if there's any?
Thanks all!
Mike

 

Mike,
Sounds very like water in your fuel tank. Check the little drain Jose in your fuel filler flap. It can get blocked with debris, preventing water escaping, and allowing it to enter the tank.
Car runs very poorly very quickly after the water gets in, but hopefully there shouldn't be too much if it was the normal sort of automated car wash.
When I had water in my tank, I managed to use some fuel, and then topped up with good fuel, and kept the process going. The symptoms diminished quickly and were soon gone.

 

Put some Heet in your gas tank, it will help get rid of the water. If your gas tank drain is clogged, you probably need to also check the 4 sunroof drains too. There is a battery breather in the trunk, but I doubt water has ever gotten in that way.

 

After a good night of rain, I finally got under the hood and started digging.

Coil packs. A pool of water under the packs in the bolts.

Bit of air cleaned it right out, runs mint again

NOTE:
Car washes pressure jets literally jet stream water under the hood. Jag hoods look pretty, flip nice, but not car wash friendly unless air tight. Found out mine was not, the rubber lining broke straight apart where it shot down my windshield and right into those CPs.
Learn from my mistakes!

Thanks all!
Mike