mister_v_man

have any of you checked the vacuum hose connection to the IAC (Idle Air Control) Valve? My '98 EB Expedition was hard to start and ran really rough. I secured/sealed the hose to the IAC (with some RTV and a wire-tie) and the truck has been running great since. It has 120,000 miles and runs great just like the day we got it. I recently changed the spark plugs on it and have never had to replace a coil pack. For those of you wondering, the vacuum hose to the IAC valve is centered located as far back as you can reach near the top of the engine. It is approximatly 1/2" in diameter, and has a 90 degree elbow on it that looks similar to a small engine spark plug boot. Your hand will pretty much be touching the firewall when you get to it. You'll probably have to stand on a chair and lean over the engine bay to get to it. Make sure it's not loose. The intermittent rough idle could be caused if the hose loosens up during vacuum changes throughout the RPM range. Please let me know if this helps anyone out.