95 Astro with code 35 blues

95 Astro 4.3 vortec engine with central port fuel injection. Check engine light comes on at idle. Idle is definitely high. Have replaced both the o2 sensor and the IAC valve, but problem continues. Instructions with the valve said to ensure the plunger did not extend more than 1-1/8" past mounting face-have made certain that it is just within that limit. Engine starts fine, idles high, and will cruise along at 60 kph (35mph) with foot off the gas. Code 35 (IAC) is the only code blinked out by the computer. Anything else I should check?
Thanks