I would only replace bad coils as needed in your case,because of the miles.
* I checked with Alldata.com and the Spark plug AJ8 4575 .035-.039
There's also a S303-S193 ECM Reflash on some models!
When removing Coils + Spark plugs label them,so you know what cylinder they came out of
during visual Inspect:
Is there a Rust residue on rubber spark plug boot?
How about any Oil residue on the rubber spark plug boot?
Any evidence of either can short a COP, and cause a misfire.
* 45k miles on a 2002 S TYPE,I would put my money on a good Throttle
body cleaning.
When you put the pedal to the metal (WOT), how does the car react?
Does the computer have to think about it?
Does the engine choke,cough,or hesitate?
Did you lose some Horse Power?
Try running a 1/4 mile with your fingers up your nose + see what you would do!
The Throttle body has a speed sensor,Air bypass valve,and a Throttle body
control module.
There's a Heat Soak time,were unburned fuel builds up gunk,carbon,or varnish on the
air intake of body.The throttle plate is a electro magnetic switch ,that doesn't
react very good when sticky!
Caution - See Troubleshoot Jag P1589
http://www.automotiveforums.com/vbul...d.php?t=968873
** I used WD40 + Oil fog Spray,micro cloth, and exercise throttle plate by putting the ignition key to the on position and pump the electronic accelator pedal.
Also use CRC MAF sensor cleaner for MAF & IAT sensors.
Note: Don't take throttle body off,just take off all the air duck work off for cleaning.
Keep in mind -''Garbage in = Garbage out''
Ambient Air-> MAF sensor -> IAT sensor -> Data->PCM
Accelerator pedal sensor-> TPS sensor -> Throttle body control ->Data->PCM
The wrong Data to PCM will cause a misfire.
I actually designed the ACME AUTO EMISSION FILTER (AAEF), to protect my MAF, H02 sensors, IACT, Injectors, Throttle body, and Catalytic converters from
being contaminated with Emission gunk, thus giving the wrong data to the ECU.
See
http://www.ideabuyer.com/ipavail/acm...issions-filter