misfire at highway speeds
 

i just purchased a 95 grand marquis which is basically a crown vic with luxury options and it has an occasional misfire i have ruled out plugs and wires as the previous owner replaced them 2 weeks before but it has an exhaust leak will this cause the misfire? im performing all the other maintainance in a week or two but any advice will help alot

any responses? just did maintainence still misfiring

Is there a particular speed the misfire occurs? If you know anyone with a scanner, have them hook it up and look in the mode$06 details. The misfire will show up under the 53 series. That will give you a cylinder to look at.

its the right bank the same side the leak is on

the misfire happens when im maintaining speed when i start up the exhaust comin out of the leak smells like its burnin really rich and the plugs on the right bank are pretty fouled up

Just curious , what are the plugs fouled with , gasoline or coolant?
First , an exhaust leak can throw off the o2 sensor for that bank and cause a lean condition which the ECA will try to compensate for.
second, Ford had some problems with other than metal intake manifolds and coolant managed to get loose.
Don't know if either of these apply to your problem.
hanky

gasoline