At 65000 miles I had to replace #4 coil and spark plug. FORD DEALER charged 254.89 This sloved the misfiring under acceleration. However now at idle the engine stumbles and shakes. Took the EXPEDITION back to the FORD DEALER. The service tech. said he could find nothing wrong. After reading a post here I replaced the Idle Air Control Valve. Still have the shakes. Any suggestions before going to another FORD DEALER? :banghead:

Stumble and shakes in park, in gear or both? YOu may also want to check your EGR system. Loose or broken vacuum lines..!!

check the vacuum hose all the way in the back by the fire wall. you can barely see it

Shakes and stumbles are very noticeable when at running temperature, ideling in gear. Have checked all vaccumn lines but will check again. Runs great other than ideling. Gets 17.2 gallons to the mile. Will get this problem solved. Will let all know what the fix was. Thanks...

Shakes and stumbles are very noticeable when at running temperature, ideling in gear. Have checked all vaccumn lines but will check again. Runs great other than ideling. Gets 17.2 gallons to the mile. Will get this problem solved. Will let all know what the fix was. Thanks...
the pcv system elbows go bad and cause the symptoms you describe. the fittig is at the very back of the engine on the upper intake like stated above.