/emoticons/[email protected] 2x" width="20" height="20" /> The C4 in my 302 Holly 4 barrel equipped 74 Bronco shifts from 1st to 2nd to 3rd within the first 200 feet or so while pulling away from a stop at normal driving speed. It shifts from first to second within 20-40 feet at 15 to 20 mph. Does anyone have any idea what causes this? I suspect it is a vacuum problem but cannot figure out what to do. Currently I'm running a rubber vacuum hose from the modulator valve to a port on the rear of my intake manifold and have replaced the modulator valve. Thanks for any suggestions you can offer.