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this really sounds like there's a vacuum leak to me or the throttle valve or idle valve is sticking open
the document you've found is an excellent guide to working through the issue
have you tried step 8 ? as this will show if any of the vacuum hoses are leaking or if its leaking somewhere else. If this is OK then I'd suggest to remove the idle valve and flush it through with brake cleaner to remove any carbon deposits and also use more brake cleaner and a lint free rag to wipe out the throttle body
thanks for the extra information
yes with the idle valve I do mean the IAC ( idle air control)
and that rubber hose you're pinching off runs to the MAP (manifold absolute pressure) sensor its the main load sensor for the engine
so check that this rubber line is sealed at both ends with no cracks or blockages in the rubber tube
if this is OK then you may have to replace the MAP sensor with a new part
well thats good to find something wrong at least
so it looks like the fast icle valve was stuck open due to all the crud.
if you still have an issue after this then check over the MAP rubber line as previously mentioned
If you want to test the effect of a shut fast idle valve can you clean yours up enough so it can seal or do you think its stuck open and seized solid?
just get back to me on this post