[alloro]

Yes, it sounds like the tranny is slipping. It might be something as simple as the low/reverse band needing adjustment.

 

[alloro]

It's not likely the 1st/rev band since it isn't engaged unless the gear selector is in 1st or rev.

Huh?? Even in (D) you start off in 1st (low) gear. Putting the gear selector in (1) instead of (D) only prevents the tranny from upshifting into 2nd, it doesn't give you an alternate low gear.