86 sovereign (xj6) - it was been running perfectly for a long time .. until now. It starts fine, idles normal, but when accelerating it hesitates and stumbles. If I hammer the gas, for instance, at 25mph, it seems like it slows down for a second or two, then sort of "catches", but not quite fully. Something is screwed. So far I've replaced the fuel filter, as it seemed like clogged filter symptoms -- no improvement.

anyone had a similar issue on the series III?
thanks in advance.

 

Yes, my 1982 Series 3 (4.2) also stumbles a bit. I did plugs, wires, cap and rotor, but still no improvement. I am now just used to it. I did buy a new coil, but havent swapped it out yet....

 

I also have new plugs, wires, cap & rotor, air filter, fuel filter - so I can eliminate those. Mine is pretty bad and not something I can ignore. I'm going to look at the throttle tomorrow, maybe try to clean it or something.

 

Check for vacuum/air intake leaks around the afm. These pop off occasionally. Happened to me before.

 

afm = air flow meter?

 

Sorry, yes AFM=Air Flow Meter.

A binding flap inside there can also cause issues.
Checked the fuel pressure yet? It could be marginal, not getting enough fuel when you drive harder requiring more fuel.