Last week,I started driving my 1996 XJ6 again, which had been sittingin the backyard for over a year. Since then the engine idleupon start-up has been consistently high (between 1800-2500 rpm). It never kicks down after warming up and pulls all the time while driving. The car will go 60+ mph on the highway without having to touch the gas. It does not seem to be the cruise control,it is definitely not the throttle cable or accelerator pedal sticking, and the brass throttle plate/butterfly has been removed and cleaned to no avail.

Also, for the first few days, the transmission kept going into "limp home mode" never coming out of first gear. After diconnecting the battery a few times and driving it a few times, this problem seems to have gone away, but the high idle issue remains.

The other problem the car has isoccasionally turning over, but not firing up.It was noticed that the cooling fans came on and stayed on duringeach failed attempt atboth warm engineandcold enginestart-ups (when car had been sitting for awhile). Upon disconnecting thewires to the temperature sensor, the car started right up, butidled rough like it was flooded. After smoothing out, the engineidle went back to running high again and stayed there. It has been through several drive cycles, but both the non-starting and the high idle issues continue.

By the way, the car did run perfectly just once in the past week. I started it up last Sunday morning, it idled high but then dropped down to about 500 rpm and purred like a kittenboth on the side roads and on the highway for about a 20 mile drive. During that drive it ranlike a Swiss watch, idling and shifting flawlessly,just like it did when I bought ittwo years ago and drove it home.However,after I had parkedfor2-3 hours and tried to re-start it, the transmission had gone back into limp home mode and the high idle was back. A brief 15 minute disconnect of the battery re-set the transmission, but the high engine idle returned.

The car has about 126,000 miles, but is otherwise in mint condition. Like I said, when I bought it, and just that one timethis week, it purred like the kittena perfect Jaguar can and should be, but it is now roaring like a lion andconsuming a lot of premium gasand brake pads in the process. I welcome any advice anyone has to offer that will help me tame this beast. Thank you for reading mypost.