'96 F-250 5.8l Poor gas mileage and missing

[Hoosur]

Hey Fellas...
I have a 1996 F-250 5.8l with 213,000 miles. Been a great truck; however starting to have a problem that i cant figure out. Last year I started to have a problem with it not firing right and loss of acceleration power. I changed the plugs...was in a hurry and on the road so i didnt change the wires. The problem stopped. About a month ago I was moving back home to Montana from Maryland and the problem began again. I got to Indiana and changed the plug wires...they were SHOT!, as well as the rotor button and distributor cap. seemed to have fixed the problem. When i got on the road a few days later towards Montana, i noticed my gas mileage had sunk to 9.25 miles to the gallon...UGH...so i got to Kansas City and changed out the OxySensor thinkin that it may have been the problem. ?#1 Are there TWO on the 96? Second, What the heck is causing the poor gas mileage...its killin me ha. My thoughts are the timing may be off but a buddy said he thought it was electronically controlled. Its most noticeable, the poor running, if i am goin about 35-40 and try to maintain that constant speed where as in the past it was if i tried to accelerate...took out two of the spark plugs and they both looked fine...was in a hurry so didnt take them all out.
any suggestions.
thanks fellas
Hoosur

[jonmark1985]

I think three O2 sensors are on the 96 and on ford V8s. I'd consider pulling a plug out again and check it out. You may have a fouled plugs from the poor spark (bad plug wires, cap, and rotor).

[Hoosur]

Hey Jon...yeah i decided after writing that post to change the plugs regardless...the number 8 had oil on it...so i replaced the plugs...still mileage is not any better...the timing doesnt "seem" to be off but could that Possibly be the prob. was wondering if the fuel pump could be goin bad and if that could be the culpret...only other thought i have is a vacuum leak somewhere i am gonna check this weekend.