Trans problem

[QuicSS]

I was driving home on my lunch break when I exited the freeway and stopped at the stoplight. when I tried to start again it kind of freereved with very little movement (acted like it was still in fourth gear). when I moved the gear selector all the way down to 1, it drove just fine till I had to shift. this worked well in 3,2,1 selector locations, but when in D4 it will no move after coming to a stop or just placing it in D4 from a stop. when on the freeway I can shift ffrom 3 to D4 and it will drop into 4th just fine, but if while in 4th if I hammer the gas it will just freerev.

it is making a rattling/grinding noise if I put the truck into d4 while stopped and when I try to give it gas.

Thanks for any input

2003 Chevy Silverado 1500 HD, 4x4, Fabtech 6 in lift, 35 in tires

54K miles, no regearing, no tune.

[95Sierra2500]

Check your transmission fluid for metal shavings, and maybe do a filter change and cut the filter open to look for shavings. You may be losing the clutches/bands and 4th gear no longer wants to engage...Though why it does it from a stop baffles me.