Morning Guys,
Let me please run this one by you to see if it might be something I can ID and fix.

Mileage: 120,000
1998 XK8 so 4 forward gears
Last transmission fluid change 35,000 miles ago
Fuel filter changed 1 yr ago

The car drives practically perfectly except for one thing. Driving normally, steady speed certainly in overdrive. Doesn't matter if cruise control is on or not.

Speed either 38 to 42 mph or 70 mph. Road turns into a long slow rise (IOW a not very steep hill).

I feel a bang bang (maybe I should not use such a strong word, but can't think of anything else). Power is relatively stable, I can't tell if she's hunting between 3rd and 4th gear, fuel is insufficient (actually that might be the best way to describe the feeling. Reminds me of the exact feeling I got driving my 1980 carburated Chevy to high rpms with a clogged fuel filter. Kind of a stuttering feeling. Maybe you will recognize/remember that.). Or its something else.

Since it happens intermittently under these specific circumstances I'm hoping it's not the tranny. Maybe I should have just replaced the fuel filter before I launched this inquiry, I've got a new one on the shelf, but I figured I'd take advantage of the knowledge here and see what you might think.

Thanks, John

 

If you’re uphill, and have gear stutter, it’s a possible gearbox low ATF level problem. Any sign of ATF leaks?

 

Thanks David I'll check.

John