So glad I found your channel again. I have an 89 Cadillac Deville 4.5. When I start it, has a very high idle, and will go down if I press the accelerator. I usually will turn the key and pump the gas once, then start it, and it will have a lower idle, sometimes too low and I gotta rev it a bit to get it to stay running. I’m thinking it’s the ISC motor, but not sure. Cat never had this issue before. Just randomly started doing it after owning it for years.