I have a 2003 Sport Trac. ~200k miles
Getting the following codes : P0300, 301,302,303,316 (Low RPM misfire on Cyl 1,2,3)
6 Months ago had the Fuel pump replaced due to a stalling issue. Also plugs, wires, filters (basic tune up) performed. ran great.
Recently got those codes. runs fine at higher RPM.
Replaced the coil, no change.
Swapped the upstream O2 sensors from left to right (to see if codes would indicate to the other side of the engine) Cleared codes. they came right back, no change.
I'm stuck. Suggestions ?
I have also ran a scanner to give me live data. Nothing seemed out of ordinary, I can publish results as well.

 

Do you notice a misfire when driving? With misfires on half the cylinders (assuming your Sport Trac is the V6) it should be very noticeable.

Further assuming it's the V6, I'd be considering the upper and/or lower intake manifold gaskets as the likely culprit since there seems to be something that would effect one cylinder bank. You might also check the fuel injector wiring harness for damage and loose connections since the injectors typically share a common B+ source.

-Rod

 

I am having the exact same issue on my 2001 Sport Trac V6. I also put on a new coil but no change. I had a mechanic say to check the compression on both sides and if the passenger side is different than the driver side then the timing chain may have jumped a tooth. I had never heard of this being able to happen but would make sense if true. I will be taking mine in at the end of the week.