96 4.0 will 1 dead plug cause vibration and 6mpg loss?

[asasial]

i have a stock 96 4.0 limited 4wd auto.
i get a hard vibration from about 1500 to 2000 rpm and still misses some above 2000rpm but runs much better. surges while driving if it drops below 2000rpm.
i've been messing with it. checked/cleaned egr, iac, maf, throttle body,
i was just outside pulling the plug wires off one at a time 1 plug seamed dead no change in engine sound. (waiting on engine to cool before pulling plug and checking it out)
my question is will 1 dead plug/injector/cylinder cause a hard vib at that range and cause mpg to drop from around 20 to 14?
thanks

 

[asasial]

it has about 190,000 miles and this problem came on suddenly. was running fine, sat for about a week or so when went to drive it, the problem appeared.

 

[corkey]

it sure will,
i had drivability issues much like you are talking about, changed plugs, all gone now,,

 

[corkey]

oh yeah , mine is a 96 4.0 as well,

 

[asasial]

i'm sure fixing the plug or whatever is causing that cyl to not fire will help but i didn't think it would cause the hard vibs i'm getting. it's annoying to drive. slower speeds ya have to take it outta OD or it will drive ya nuts. and the range is funny. just as soon as it gets over 2000rpm the shuttering/bucking completely stops but ya can still feel a miss in the engine.

 

[corkey]

it will

 

[asasial]

100% improvement. the plug was bad. replaced it with the only spare i had. feels like a new truck compared to before. gas mileage is already up to 16mpg on back roads. better than it was getting with city/highway driving. still a very slight miss in it but i'm sure new plug all around will cure it.
thanks again.

 

[SoNic67]

You might want to replace all plugs with new ones at this point. There are all the same "age"...

 

[corkey]

you're welcome,,

lol,