Got a 1986 Ranger with the 2.3 four cylinder with about 320,000 miles. Last year or so as I drive down the road usually at highway speed the Truck will suddenly buck. Like the engine dies but comes right back. Doesn't happen under load like during acceleration but usually at highway speed. Sometime's I can go all day and it doesn't do anything other days it's bucking every few minutes. Thought maybe an injector clogging or going bad but it's worse than momentarily losing a cylinder. Jars the whole truck when it happens. Like loosing the ignition for a second. I have replaced the MAP sensor, plugs, wires, distributor cap and button, ignition module and distributor assembly. I pulled the injectors to clean and rebuild them and they all checked out good. Both high pressure and tank fuel pump have been replaced within the last year including the fuel filter. I have gone through as much of the wiring harness as I can to clean all connections including the ground. As of now I'm at a loss as to what to do next. I've been hoping if would would just break down completely so at least figure out whats failing. If anyone knows what I need to look next let me know. Thanks

 

I would start it and do a wiggle and thump test on the wires controling spark to coil and to ignition systems and see if you can make it sputter. Sounds like you are losing power then regaining it

 

Ive done that and nothing changed. It happens so quick I don't loose any speed before it restarts going down the highway. It sure jolts the truck.