[firechicken]

I bought this little car on a whim. It's quite fun but has an issue I'm trying to diagnose and rectify. I'm no expert with OBD2 stuff but do have a scanner and other tools. I know there's a few efi smart guys here that might be able to help.

This is a 1999 Jaguar XK8 with a 4l V8 and I believe it shares parts with Ford.

It mostly runs quite well but has a tip in stumble I can't isolate. Easing into the throttle is fine but a quick snap open gives what I'd call a lean lag like a faulty pump shot on a carb. If I snap to wot it bogs bad enough it won't recover and throws a lean code. I've smoked the engine and did find a small vacuum leak but nothing I felt would cause this.

Fuel pressure seems good. Coil packs and plugs are good. Fuel trims are not out of walk as far as I can tell but ST does go straight to 25 when I snap the throttle and create the bog. If I disconnect the maf it seems much better. I've cleaned the maf with no difference and it appears to be functioning properly on the scanner. O2 sensors appear correct as well. Throttle body seems fairly clean and working properly.. I'm pretty much stumped.