I called Edelbrock tech line. My 800 thunder has same problem. He told me to go bigger on the squiters. To go to the 43's. He also told me to put the orignal jet's and rods back in. We had tried smaller main jets. Didn't help. More timing helped but didn't cure the problem. He told me off idle stumble is caused by not enough fuel coming from squirters. If moving the rod to top hole didn't cure it it needed bigger squirters. Just ordered a set. Will try them out saturday.