1 pointAll paid, and looking forward to this.
1 pointAs ghost said , have a look in the tech section at the sticky thread on how to self check for ecu codes and reset the ecu . Unfortunately i haven't doen electrical tests on later classics and don't have a service manual for the v5/v6 , so can't help with voltage readings. The idle control valve and maf can be cleaned with electrical contact or brake cleaner , both of which tend to "gunk up". Just bear in mind ,You'll probably need a new gasket for the icv (from import car parts) if you do remove it to clean it .
1 pointHave you checked the ECU for any error codes? There is a guide on here for how to do it. On classics, there are two black connectors below the steering column. Connect those up, turn the ignition on and count the "check engine" flashes. A long flash is a 10, a short flash is a 1. I'd recommend videoing the flashes so you can watch it back. Once you have your numbers check them against the list on the forum. There is also a guide on how to clear the codes.