86 300SDL trans just started slipping 1st to 2nd
 

Hi,

Okay I am guilty of not doing much homework before posting about this issue but it just started and I am going to be busy next couple of weeks with not much time to tinker.

The trans was shifting a little hard on the slow speed shifts but since still getting the fuel and boost dialed in I figured the fluid was next and then test the modulator and the linkage.

But just today in, oh 80 degree weather it started slipping a little between the 1 to 2 upshift. I am thinking new fluid is likely to cure this.

Any direction worth noting if a filter and fluid change does not do the trick?