When mine was misfiring, it was fine at idle and on heavy throttle. I pulled the back coil and it had water tracks running down into the plug well. I've read the issue is due to leaking washer jets and the under bonnet sound proofing hides the issue, so that's why people remove them. No signs of leaks on mine though
The IAC is bolted onto the front side of the throttle body plenum, look for the valve with the diamond shaped mounting surface.
My car does spring into life with minimal cranking or fuss, then settles to a nice solid idle. Check all hoses that that connect to the air intake pipe as anything that's come adrift will cause an air leak downstream of your maf and effect all running apart from WOT.
I understand the orange clip (if that's what you mean by pump clip?) is purely to stop the fuel filter falling apart as they can do. It's on passenger side of tank under the rear seat. It won't cure any other problems... and you would know if you needed it as you'd be stuck at the side of the road.
Not sure where the viton seal goes, maybe this is the seal between the two halves of the filter. I'm still learning about these engines so others will probably have more definitive answers!
Rich.