My van will not shift out of first gear when you pull off, why?

Hello, please ensure the throttle valve cable is attached to the throttle. This will be a cable coming from the transmission area, and if it's disconnected due to a failed grommet, it could spell all kinds of problems for you and the AOD automatic transmission you likely have equipped in the vehicle (could also be a C6 or E4OD, but less likely). The TV cable grommet is like $5 and it could prevent a $3,000 problem oddly enough. If it's not that cable being detached, and again, if it's the AOD transmission, keep in mind this is a totally hydraulic and vacuum operated transmission with no electronic inputs. This means you would look at vacuum modulators, internal valve body components, band adjustments...old mechanical transmission stuff that 27 years later we don't deal with so much anymore! Good luck.