1999 LT Tahoe. - Is it the trany speed sensor?

[RoyC]

1999 K105 2door Tahoe LT. 5.7 sfi.

I have recently had an inlet manifold water leak fixed & a new electronic transfer box fitted.

My problem is:- When crusing at around the 60mph mark the engine sound keeps going up & down, as if it is changing up and down gear, If I accelerate, it stops doing it (the rev counter seems to stay steady), also when I accelerate hard from a standstill, then it goes into neautral and the engine screems, when I ease my foot off it goes back to normal acceleration.

Could this be something to do with the trany speed sensor or do I have to look elsewhere?

Thanks,
RoyC.

 

[GMCYukalade]

Might be the torque conv. or clutches slipping - you can check the conv. take the dust cover off and look at it, see if it turned blue - if it has than it probably needs to be replaced