My new to me '93 2.4 accelerates fine and idles without dying but seems to have a frequent stumble/shudder. It passed smog in California recently and PO had replaced plugs, cap, rotor and wires. Truck has 175,000 miles on engine. Any thoughts or ideas? I really have no complaints about engine under load. Do our engines like a specific plug? I need to check ECU to see if it has been reman'ed and I will most likely send out injectors for cleaning. Fuel filter looks old (just picked up a new filter which I will replace this weekend) and not so sure about EGR though to pass smog, system must be fairly clean. Perhaps timing off slightly? Thanks!