I recently purchased a Jag XJ40, 4-litre auto (1991). I didn't notice any
problems on the first day I got it, but twice today I've had a problem where
I start the car up and it ticks over fine (though the car does judder a bit
more than I would expect - timing out perhaps, or maybe sparks need
replacing? it does idle at about 750 rpm - is that too low?) but as soon as
I shift the box into reverse or drive it stalls. This happens 3 or 4 times
and then it sets off fine, and hasn't stalled at traffic lights or anything.

The oil pressure in the car seems fine (usually just over half way on the
dial - 5-ish), temps OK and there are no warnings reported by the ECU. I
followed the instructions in the manual for checking the gearbox oil level,
but couldn't get a very good reading.. that is, after I clean the dipstick
and push it in/pull it out again, there's a thin film of oil all the way up
the stick (past the "hot" marker), no matter how many times I repeat the
measuring process. I'll have to have another go at this, but the gearbox
seems to work fine after the initial stalling episode.

Two things I am wondering about - when I bought the car the guy at the
garage said that when they got it they had to change the battery and they
got standard cheap one from their regular supplier.. indeed, the central
locking didn't work at first, but it had been sitting for 4-5 weeks at the
garage and after I drove it the 100 miles or so home and took it around town
a bit the locking suddenly started working and it's worked without fail
since. However, do Jags have a heavier duty batteries fitted to them
normally, given all the electrics they have in them? If that is the case, is
it possible this is the cause of the stalling (OK, maybe that's daft since
it starts first time and it's only when you shift it into gear that it
stalls, but I have to ask as I'm no mechanic!).

The other thing is that I thought I had read somewhere in a bit of
documentation that came with the car (there was loads of stuff!) that the
car would take 95 ot 97 RON unleaded.. but when I was going through the
manual I found a bit that said "use only premium unleaded".. isn't "premium
unleaded" the 97 RON stuff? could that cause the stalling maybe?

Any ideas on this stalling issue, or for that matter - how to get a clean
reading from the auto box dip stick!?

Thanks
Ian