Jerking, 1989 Ford Ranger 2.0L

Hi all,
I bought a 1989 ford ranger for 800 bucks 2 years ago now, fairly high mileage (253,000KM) it was a great truck until about a month ago. 4 speed and O/D 2.3 4cyl engine. It idles quite good. My problem is when i'm driving down the roads in town in 4th gear at 50-60 km/h it will start jerking, i am pretty sure its not a clutch because it isn't reving up. If i'm doing the same speed in third gear it seems to be fine. Same thing down the highway in od, 100 km/h its jerking. 110 km/h its fine. seems to do it around the 2000rpm mark. ALso it is making some kind of ticking noise after its been started up and goes back down to 850 rpm or so. What would the problem be?? Fuel Filter, Plugs, Plug Wires???

Thanks in Advance

Sorry, 2.3L motor not 2.0

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.

To add just a bit to this discussion:

I believe the two plugs are actually hooked up in series with the coil in between. So "normally" both plugs will fire together ... one plug's cyl is nearly TDC on the combustion/compression stroke ... the other plug's cyl is nearly TDC on the exhaust stroke (sometimes referred to as a "wasted" firing).

The second spark plug in each cylinder is there as a total duplicate of the first plug (perhaps with a slightly delayed firing) ... I believe the concept is better flame control as the fuel is ignited more uniformly.

BTW, I just went through this exercise on my SIL's '94 4 cyl, 230 kmiles. I have no words of wisdom. I just threw money at it ... replacing everything, but avoiding the high priced ignition module. Finally there was nothing else to try. I first bought an aftermarket unit that was no good. Then I paid the bucks (actually less) and got one from Ford. That did it!

Will try that, It is a dual plug engine and the 4 plugs/wires on the left side of the engine look like there going to be fun to get at