hello. I recently purchased a 1997 XK8 4.0 with 42.000 miles that had been sitting for a while. it is losing power when accelerating and stalls occasionally when driving. I changed the fuel filter, it had the lovely old orange gas present. after running 2 full tanks of 93 octane and 2 more filters, there's no improvement. fresh set of plugs installed today. I'm not sure what to check next, any help is greatly appreciated. bill

 

You may have a gummed up fuel pump sock filter. Its inside the tank, naturally. The pump may be gummed up too.

 

Bill ,what is orange gas? Do you have an OBDII to read codes?
any air leaks in convoluted hose between air filter and throttle?

Just some lite brainstorming, checking the codes is important.

John