What year/make/model is your car? How many miles are on the trans? What engine and mods if any do you have? Does this problem happen during normal driving or just heavy throttle? A worn boost valve is typically not the first thing to blame for a slide bump shift and if it is that bad then you likely have a code P1811 for excessive shift time. A Transgo shift kit greatly helps these transmissions to quicken up the shifts but if your trans has been slipping for a while and or the clutches are worn or burnt then fixing the route cause of the problem doesnt necessarily mean it will make the trans work how it should because the damage may be done. Pressure control solenoids in the 97-02 models had a very high failure rate and cause a lot of pressure related problems.
