98 gmc 1500 350 4x4

Used to get 18-20 mpg on the highway, replaced catalytic converters, plugs, plug wires, dist cap, rotor, oxy sensors, fuel filter. now the best I get is 16. get occasional misfire on #7-could it be evaporative emission control charcoal filter? open to any ideas. have 111,000 miles on trk

Reply to
cowby
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Did you replace them or remove them? (The CAT'a)

Reply to
TheSnoMan

All items were replaced.

Reply to
cowby

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