My 1997 C230 shifts very eratic, if left in drive and excelerated normally it will act as if it is in neutral when shifting into 5th gear and it does simular things when starting off in 4th.It drives down the road great it doesn't slip once it is going down the road.It also has what sounds like a vac leak under the dash on passenger side that only happens when the a/c is turned off.It is coming from a little box with about 8 colored vac lines going to it.What is this box? It also gives the code PO700. Can anyone help me figure out something?

 

P0700 Transmission Control System Malfunction

Pull the carpet from the passenger footwell. Do you see any oil at the bottom of the footwell? Unscrew the metal plate. There is a black box atttached to the back of the plate. Feel the wiring harness. Disconnect it and squeeze it. Does oil come out? If so, then you have the infamous transmission fluid migration problem. That little black box is the transmission ECU and it can get messed up by fluid that leaks from the tranny and migrates through the harness. There are many other possible causes for your tranny problem but is one we all should watch out for.