no they didn't replace the idle valve, they replaced the a/c evaporator. i too completely removed the engine cover. the gaskets looked okay, but i'm no expert, so they very well may have been damaged. i would say i only put on maybe 300 miles before i figured out the engine cover wasn't seated properly.
and i don't know if my engine cover is defective/crooked or what, but i had a hard time seating it properly too. it just would not sit straight. all 8 "trumpets" would not fit into the throttle bodies tightly. it's like it would rock to the front and the rear, but would not go down flat on all 8 throttle bodies. so i just pushed it down straight as far as I could and tightened the screws. thanks for the tips though.
“For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.”
- John 3:16