I i have a 2001 s type 4.0 with 85K miles. California car for 16 years now on East Coast. When I drive the car on the highway it starts and runs great. After about twenty miles at highway speed (55-65);When I stop and rpm drops to idle speed of about 700 rpm the engine surges up and down about 200 rpm but does not cut off. Usually when I accelerate it’s fine again, but today it continued to stumble through the gears up to 55mph. I stopped for about thirty minutes for lunch and started home again. Engine ran perfectly the entire return trip of about fifty miles and several stop lights. Wondering if maybe I have a dirty injector? I run 93 octane only. Also wondering if the car going from SoCal weather after 16 years to the heat and humidity of coastal va might be trying to reprogram the computer or fuel air management system? I’ve only driven it about 400 miles in the last eight months of owning the car and it is garage kept. I’m new to jaguars so forgive any simple oversights on my part. Thank you all very much

I will check both of thos items. Thank you

w myrphy

hi there. Did you complete the chain gang replacement? Mine was sussessful. Note I used Christopher’s foreign car imports aj v8 full kit replacement. He is on eBay. It is a full replacement kit. Chris was great to talk with and helped me with a few technical points. Chris formerly had a Jag shop. Don’t forget to install the dime sized o rings on the vvt cam holders. They go between the holder and the block. Mine had fallen off when removing the holders and I did not know where the last two o rings went. Use vasoline to hold them in place. Note I had to remove the oil filter housing to slide off the crank damper. One of the pipes was in the way. So buy the figure 8 gasket to re install. This is the only gasket not in the kit. See my pictures and write up which I posted. 52 hours all in. However I had some rework because I had to find where those two o rings went. Best John

Thanks for getting back to me with this information. I’m sorry it took me so long to reply. I’ve had to put a few things off for awhile due to a variety of reasons, but mostly health. My Jag is still in the garage not to be driven very much until I get this job completed. I hope I can start it in the spring and get that problem off my worry list. I’m going to see if I can find your pictures on the forum, that will help a lot. Thanks for the tips and the source for parts. I’m glad it went well and your back on the road....again apologies for being so tardy in replying.

I don’t have the workshop manual. Is that a link to it?
Thanks......

Thanks for the link, but when I copy and paste it to my browser it says the media fire file it’s calling for is no longer there or can’t be accessed. It may be something I’m doing but do you have any other ideas or ways I can get to it? Thanks for your time.

Thanks for the suggestions. I did buy an OBD2 with Bluetooth and it worked really well. Fuel trims were fine long and short term, and throttle body looked clean as a whistle. Plugs looked pretty good but while I had them out I replaced all eight plugs and coil packs and it ran great after that. Suspect I had one coil pack bad or intermittently failing.

thanks again for your suggestions