2001 Focus LX speedometer jumps like tachometer when reving motor

I bought this car a year ago with 66k it now has 69K. the problem started a few months ago when I would shift into 3rd gear at low RPMs the car would buck a bit. if I went into 3rd at high RPMs I had no problem. now I can feel the hesitation (like lack of spark) in any gear at low RPMs and the speedometer jumps when you put the gas peddle to the floor in any gear at low RPMs. (the motor does not rev when the speedometer jumps) also in neutral if you rev the motor the speedometer jumps. the clutch feels fine and is not slipping. if you wind the motor high through the gears the speedometer acts normal.
I replaced the fuel filter and complete tune up plus cleaned all 4 body grounds. I brought it to the ford dealer for some recalls and asked them to look at it while it was there and if there was a recall for this problem. I also asked them to keep it cheep, they test drove it and checked for a bad ground & found all were good. they tested the speedometer sensor on the trans and that was fine along with all wiring. they gave it back to me saying they couldnt find the problem it's going to be a costly repair that would take a long time to figure out. charged me $68.00 for 1 hour labor to look at it.

I was wondering if it might be a bad coil pack or a ground on the coil pack, if anyone has any ideas please don't be shy just reply.