My 2004 XKR is having a small hesitation under moderate to low medium acceleration driving 35 to 45 mph. The rpms pick up then drop back for a couple moments then picks up again. If I accelerate harder it takes off fine, like it bypasses something on strong acceleration. City driving you'll never feel it . Fuel filter, MAF, have been changed, air tube is tight on both sides, stock air filter is new. 50k miles Im running some cleaner through today and tomorrow. It may have started aftet I took off the fresh air tube off to inspect it, ckean MAF and inspect filter box, but I replaced the MAF no difference so I took it back. The Specialist EURO car shops say if it has no code we can't diagnose nothing. They drive it and can't feel it. Really, i assured them its there but no code they send me away. Exasperating.
Thank you in advance.

 

Long shot but make sure the bolts securing the air tube to the throttle body are still in place. I had similar issue once when a bolt worked loose.

John

 

use the frp sensor it will tell you if you have a pressure problem. then check the many other pids to see if the numbers add up

 

Thank you but my Air Tube fastens down with a band that tightens down with a screw adjustment. See pic.