Lohanso

The engine starts with a RPM around 2000. Somewhat nerve-racking on a cold start. The IAC will step down the RPM in 2 to 3 step downs .. sometimes requiring up to 30 to 40 seconds. After warming up there is no improvement .. .

Driving sometimes feels like I'm on cruise control ... the only way to pull the idle in range is to slow to a stop where finally the vehicle speed drops below 5 MPH which seems to override whatever is causing the high idle . This is a 1997 GMC Seirra 4.3L manual transmission.

Cleaned the TB, checked the TBP, replaced the IAC, replaced two sluggish O2 sensors (before and after the cat) ... Cleaned the EGR valve ...have temporarly installed a plate between the EGR and the manifold to verify the valve is not causing problem by leaking by...

After the IAC has caught the idle and brought it to normal I can unplug the IAC and the truck idle problem goes away, even starts up without the racing RPMs. Hot or cold start. Any ideas out there .....?

Problem started immediantly after a water pump replacement @ 117K miles .. go figure

Lohanso

Going to pull EGR valve plate and return it to operatng status as this didn't provide any clues .. note: ran disabled EGR valve unplugged and plugged to see if I/O data from the EGR might influence the idle .. didn't make a diff..