this does make sense and doesnt, i used my friends computer and got the same problem when his didnt do it, but when i pulled the bosch plat2 the other day they were white which normally means lean tan is good if i recall correctly i know the pressure regulator vacuum hose boot was bad but replaced it and it didnt help, honestly it didnt do it before i changed everything, when i got it it had 193,000 miles with all stock parts i did the usual tune up and thats when the crank sensor died so i replaced it problem solved, thats when the skip started. So we put the cam sensor on the o-scope and it tested bad when i replaced it it made it better but it didnt fix it, the skip used to be 1500-2500 so the cam sensor just narrowed it down. i have also been told the distributor could be worn so it spins more in an eliptical pattern than a perfect circle. Back to the tune up, the stock fuel filter was still there and the stuff that came out of it was more like motor oil than gas, could the filter need to be changed again only put 1,000 miles on it since i got it a month ago? The guy who did this with me was a GM, FORD, and now a NISSAN tech but he has driven nothing but XJ's since he was 13 and he is now stumped all his fancy stuff couldnt tell him either.