Random cylinder misfire problem (p0300)

[SHUTTERBUGMC]

HELLO, I’VE BEEN UNABLE TO LOCATE A RANDOM CYLINDER MISFIRE PROBLEM (p0300) ON MY 2001 MITSUBISHI MONTERO SPORT. While having the timing belt replaced in April 2006, a “dry start” was done. My mechanic obviously paid the cost of this repair, using genuine OEM parts, but I fear this is triggering this ongoing issue. This problem, characterized by the engine hesitating or jerking, like it’s not firing on all cylinders, does not appear until the engine warms up, usually driving approx 50 miles between 75-80 mph. This first happened May 2007. The random misfire code traced back to plugs/wires and a reflash, so I had both replaced and had the reflash done. The same thing happened over new years eve weekend. Diagnosis revealed the same random misfire code, and plugs/wires checked out fine. There have been no problems until this past weekend, when the hesitation occurred twice while traveling long distances. By slowing down to between 60-70, the hesitation went away and the engine light did not come on. Something has got to be wrong somewhere. Please help!