1999 Intrigue GLS(3.5 L) transmission slipping.

My transmission is starting to slip. I had a rebuilt engine installed in it last year but the transmission has about 120k miles.

Any advice on what I should do?

Should I add a transmission additive like lubeguard or have a place that works on transmissions take a peek at it?

Any advice would be most welcomed.:popcorn:

I would have a tranny shop take a look at it. If you are not comfortable wity that then change your filter and fluid " do not flush" This may fix it. If the tranny fluid does not fit it then you better lesson to a pro. You may need a rebuilt at this point.