I just bought a 99 runner w/ manual transmission and 65k miles young. The idle is slow to come down when the clutch is pressed and then fluctuates between 1,000 and 1,100 rpms. The truck also has a slight hesitation when trying to maintain a constant speed w/ rpms around 2,500. I cleaned the MAF sensor which didn't seem to make any difference. I gave in and took it to the shop. They replaced the IAC valve, which wasn't cheap. That helped, but hasn't solved the problem. Has anyone else encountered this problem? Any suggestions? I was thinking of changing the plugs, but thought 65k miles is a little early.

 

I changed the plugs today. The truck runs much better, but the hesitation/surging is still there. Seems to be most pronounced in 2nd gear at 2,500 rpm. The mechanic suggested replacing the MAF.