Inspect the wires at the throttle switch first. They sometimes come loose from the plastic harness plug or have frayed wires.

You don't have to remove the throttle switch to clean it, although it is removable.

You do have to remove the plastic cover.

If it is the later style, the plastic cover is held on by fragile plastic tabs that are part of the plastic cover, so flex with care. Also make sure not to lose any of the little rubber bumpers that are inside the plastic cover mounted in each corner. They usually stay in place, but occasionally fall out or get stuck to the corners of the metal backing plate.

Removing the cover exposes the PC board and I suggest using a clean natural rubber eraser over the path of moving contacts.

Then wipe with a clean cloth. It is okay to test with the cover removed.

It sometimes takes 2 or 3 attempts to get it clean.

If cleaning doesn't solve the problem, I have NOS (new old stock) throttle switches or I have replacement PC boards if you have the later style of switch.

Good luck,
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com