I just bought a used 2004 Freestar 4.2L with just less than 110,000 miles on it.

While in relatively low speed and low RPM, the RPM jumps up and down. I noticed today that while going about 30-40 mph at RPM around 2000, the RPM jumped around between 2000 and 2500 and I could feel some slight shudders. I talked to the previous owner and he said it's the fuel filter issue. Thoughts on this?

Also, I was driving up a slight hill yesterday and the "check transaxle light" and "check engine light" both came on and started to blink. I pulled over and killed the engine, checked fluid levels, saw that the engine oil was a little low (luckily I had a quart on me), filled it to normal range, and started the car again. The "check transaxle light" turned off but the "check engine light" is now on solid. Oh, the transmission fluid level was higher than the upper hashmarks on the dipstick. I took the car to the dealership today to get the torque converter recall done, and asked them to check those issues out as well. They wanted to charge me for it but I got them to just check the code at no charge without doing a full diagnostic at this point. Does anyone have insight? Once I find out from them what the exact code was, I'll update it here.

 

When that check engine light is in the flashing state it is telling you that there is a serious emission problem that could destroy the converter if ignored. Good that you had it looked at as quick as you did.

 

Don't know what the "fuel filter issue" is. Never known Freestars to have a problem with fuel filters other than an excessively dirty filter from not replacing one (like any other vehicle could experience). I do know that I replace my fuel filter every 30K miles as I see my mileage drop a couple MPG around that mileage frame. My fuel filters have always had crud in it and a new filter bumps my MPG back up to it's normal range. I just recenty replaced mine, but before the 30K point as the MPG had dropped. Who knows what was in the fuel tanks at the gas stations I used on the latest trip to AZ and back. You could have a filter that is dirty enough to cause fuel starvation (the shudder you were feeling) which in turn can make the computer clock LEAN and MisFire codes.

Were you able to get the codes that were read by the Dealer?

 

The previous owner said he had the same problem, and it was solved by replacing the fuel filter. However, the filter was replaced just 8 months ago. I did some research and I think it's more likely that it's an ignition pack issue. I'll change some parts and see what happens.

 

There is an electric motor actuator on the left side of the intake manifold looking at it from the front of the car. It has two wire linkages that go from the motor unit to each side of the motor near the heads. These linkages actuate plates in the intake plenum that open at around 1600-1800rpm. Where these linkages hook to the plates, they go into small plastic grommets. When these grommets wore on mine (@130,000 milles) the car would jerk very slightly when cruising with the throttle open slightly, or going down a slight hill with the throttle open slightly. The play in the grommets would cause the plates to wiggle just enough cause the motor to jump RPM slightly. They were about $8 for four of them.

look at the last post in this thread for a pic of what I'm talking about.

https://www.fordforum.com/forum/ford...-tuneup-30488/