my 99 expedition misses real bad like it going to stall have change alot of hoses and other stuff can someone give me a clue what else it could it be or could be the air filter. thanks for your time in this matter.

 

you should have coil over plugs. the #4 cylinder coil is notorius for burning up on the 99's. i've had this happen myself. it is located on passenger side near the firewall. apparently moisture collects back there for some reason and causes the coil to fail. you may check that. i don't know how to check it unless you have a code reader. if you do and a cylinder misfire code comes up, it will say which cylinder it is. take that coil off and swap with another one on the engine and a code will come up on which ever you switched to. if this is the case then you know the coil is bad. they are between $60 and $100 to replace. not saying this is your problem but it is very common.

 

I agree with said above. Should be able to unplug your injectors 1 at a time while engine is running and watch for noticeable changes in engine performance. This will pinpoint your coil misfire.

 

you guys are on the money my 99 expedition had a bad miss and it was the passengers rear coil which aparently gets wet from those cheep heater hoses that leak antifreeze on the coil and shorts it out i have changed mines twice and i just looked at it today and saw it wet so it seems hard to change the hose so im gonna cove the coil with a peice of rubber so it won't get wet good luck