I have a 2004 Freestar 4.l Limited thats been babied its whole life.Oil change every 3000-4000 miles,scheduled maintenance etc,except for tuneup..It has 83k miles on it and for the last year when i go up a slight hill it jerks a little or hesitates.On a flat road it is strong and runs perfect,seemingly.. This week when my wife starts it an goes to back out of the driveway it misses a bit then drives normal,but again on slight hills it jerks a little but seems to go away if i accelerate.Today the check engine light comes on and seems to still drive good other than the light jerking up a hill or under a load...Autozone code shows p0303 and p0316 which is soem kind of misfire so i assume the jerking was a misfire,hesitation or something like that. I was thinking it was a transmission issue but guess not...anyway talkin to the Ford dealer he was saying..i think...That they are notorious for Exhaust manifolds leaking and sucking air and misfiring,i think he said but a little research im seeing other things like coil pack,plugs,etc...Is it dangerous to drive?? long term harm to the van?? Ford dealer said no it was not harmful.This weekend i will change plugs an wires as it has been 50k+ miles ..Looking for advice,opinions any help or guidance i can get. Thanks for your Help !!!

 

The jerking and misfiring doesn't do the engine and tranny any good as there is quite a bit of component "HAMMERING" that happens when the jerks/jolts occur. I had the same issue with my 04 around the 70K mark. A new coil cured it. I would replace the plugs, wires and coils with a new. I'm running NGK Irridum spark plugs along with OEM wires and coil. My 04 hasn't peeped a misfire since. Make sure you use dielectrical grease inside the plug wire boots to eliminate spark leakage.

 

Assume you fixed it with the coil. I think mine was damaged when they did the tranny recall. These guys are NOT top of the line. They left half of the stuff unclamped.
You may damage your Catalytic converter running extended period of misfiring.

 

Mine is 110,000 miles and regular maintenance. Started misfiring this past week and the check engine light came on. I'll get the codes tomorrow on the way home.

I also had the torque converter recall, and the car ran worse after. I managed to take care of the problems (fuel pressure sensor and some nylon bushings) for about $600 less than the dealer wanted.

I'm pretty sure it's plugs and wires. Coil will be the next thing afterwards - $40 at Rockauto.com. It still sucks, but it's not too hard to get at everything.

11/28/13 -

PS - Got similar codes: cylinder 1, and misfiring in first 1000 cycles.

 

My 4.2L started with random misfires around 75K and I replaced OEM plugs with Bosch Platinum 4012 single electrode plugs. The engine seems to like them just fine and they were inexpensive too - only $1.50 each. Costs more to change the oil on this vehicle - go figure.