New (to me) Ranger with a Problem

[Hack2ey]

Hi all, I just bought a 1990 Ranger 2wd with a 2.3L four cylinder and a manual transmission. This truck has about 100K miles on it, and I don't know whether it's ever been tuned up or had any service to fuel injection or ignition components (like new plugs and wires or a cleaning of injectors or Idle Air Valve).

Anyway, the problem with it is that when accelerating through the gears it runs fine and pulls hard from idle up to about 2400 rpm, but between 2400 rpm and 3000 rpm it hesitates and does not pull cleanly. It feels as though it is leaning out in this rpm range. Fully opening the throttle helps it get through the hesitating range and at about 3000 rpm there is a noticeable surge in power and it pulls hard and clean again until I upshift.

Any ideas what could cause this?

 

[KnockKnock]

My first thought is fuel filter, but at 100K miles, it's time for the all-around tune-up anyway. I bet you've got a shot at taking care of this with just some routine maintenance.