99 xlt 4x4 tranny shift question

[00GT99XLT]

Ok so heres what it is doing recently. Sometimes under light - medium acceleration it feels like the tranny is "hiccuping" and the 1-2 2-3 and so on shifts are hard or it slips slightly. So after it did it the last time i turned down a nice long road, stopped then masched the throttle down. Every shift was smooth as silk, then after i did it the light - medium shifts were fine. It just started doing this. I recently did a Filter and used Valvoling 75K suitable for Merc V. I did pull the dipstick it was readding higher than the crosshatched line.

ANy help or guidance would be greatly appreciated. Thanks guys!

Oh and from what ive been told, the transmission has 120K + on it.

 

[00GT99XLT]

Anyone?

anyone,,,, bueller???

 

[BrooklynBay]

Are you getting a shift flare or is there another problem?

 

[00GT99XLT]

Yes it does flare, and the shift is hard. A thunking or knocking sound can be felt as well.

It did this one other time when i was going up a VERY steep grade.