[Ecm Medina]

I have a 90 Ranger xlt- 2.3l 5speed with dual coil distributerless ignigtion- I have a "jerking" problem that may be like yours- At low rpm,loaded in gear if you floor it it bucks,or if at hiway speeds (55-60mph)if in OD and traveling uphill and add gas it bucks if missing.When rpm is over 2000 rpm in any gear or starting out in first from stop and shifting up during normal accel it doesn't do it.
I have replaced both coil packs,ignition module, air charge sensor, all eight wires and plugs, o2 sensor, throttle position sensor,and the fuel pump and filter have only a few thousand on them.Idle is operating normally cold start and when warm it feels as if one cylinder may not be firing but, putting timing light on each wire verified they are getting discharge from coil. If this sound like what you have , do not go spend a bunch of cash on sensors ect...
I think with 170k on the odometer the head has blow by on an exaust valve of a cracked/worn ring set that is not letting enough compression for the ignition coil to allow the correct plug to fire. The paired coil half in each pack recieves a pulse to fire on the primary wiring and the density of the charged cyclinder on compression stroke creates a path of least resistence for the spark to travel to the appropriate plug- the other paired cyl is on the exaust stroke and is less dense thus higher resistence on the plug. My next action is a compression test and to actually charge each cyl with compressed shop air with a regulator and listen for air flow from the exuast- verifing an exaust valve or from the intake manifold for an intake valve as well as the pcv outflow from the lower block (it is below and aft of my egr valve on my truck ) to see if the rings are blowing by. If air is blowing by, then it's a head recondition or bore honing and ring set to repir I'm afraid.
I will let you know what I find and good luck in your trouble shooting. I hope this helps you.