There is also an issue called the 1-2 "Bang shift". You pull out from a side street & let off the gas just a bit - BANG it hammers into 2nd. A little part called a TSS (Turbine Speed Sensor) should fix this problem. There are posts & How-to instructions available. Costs maybe $20, takes about 5 minutes if you're handy - 15 if you're not. A few have had difficulty removing the old part because of rust, so you might want to take it to a shop to have it replaced since you have an older model.
Is your "slipping" happening in reverse 1st thing in the morning? Does the slip go away once the tranny has warmed up a bit? If so, do the valve body thing as stated in the above post.
