Clutch slips badly in first gear, - 2000 GMC Sierra

MT trans. got it. (said clutch let up.. is the clue)
engine is running right? (sorry)
and you shift to all gears, and car does not move, RIGHT?

if the clutch slips and car will not move in ALL gears.
the clutch is bad, or if a cable clutch, never setting free play on cable is the cause,... done 100s.
or if hydraulic actuated clutch pedal (im too lazy to look)
then if it fails the car can only moved if you start engine in gear.
see?
please post all steps.
i get in car,
i start engine in neutral. (did you) or start in gear with clutch to floor.?
i then select all gears, and release clutch and car will not move.
like that.... and win. (i can diagnose any clutch, ive wrecked many racing, so.... see all horrors) and fixed them by self. all.

if you can only move car , starting engine in gear.?
that is bad clutch cable or actuator (slave or master cylinder)

is the clutch locked all times, or slips all the time.
see? only that need be said.
and 10 other symptoms. (chatters, noises, grabs, etc)

If the car heats up trying to generate revs , then it Seems like the clutch plate is slipped.

before you go ripping the gear box out check out the clutch action as a clutch will slip if the compensation port in the clutch master cylinder is blocked . If it is a cable clutch the same results occur when the inner cable shreds and jams in the outer cable.

usually a slipping clutch is a bad clutch
the acid test is to remove the slave
point car in safe direction ,
start car in gear, does it slip now?
yes, then the clutch is bad.
you do this test off road safely..
it can only be 2 things, think about it.
1: bad clutch 99%
2; a seized ,while extended slave.

So you can race the engine in neutral, and no problem with it trying to die? If that's so, I think you need a clutch job. A clutch disc contaminated with oil or grease will cause jerking and slipping.

Sounds like the clutch is slipping. If the clutch is bad, it will slip in high gears (4th & 5th) but seem to work fine in lower gears. Clutch probably needs replaced but have a mechanic check it out first because it's a fairly expensive job. If your clutch is actuated via a cable (not hydraulic), it may just need adjusting.

it sounds like its slipping, a burning plastic smell is a good indicator of a slipping clutch.but it may just need an adjustment, plz rate-bozcro

if its manual sounds like your clutch could be slipping does car smell of burt clutch?
check cluth adjustment
may need new clutch
do stall test with hand brake on, foot (heel-toe) on brake and accel pedal to about 2000rpm then let out clutch and car should stall if engine revs go down and engine still runs but you can rev causing slip and you will now smell what slipping burnt clutch is replace it.

if its auto check trans oil level and what does it look like red-good
darker red to black-bad often smells burnt also possibly new trans required.

sorry to say but you wold have to change the clutch its really not that bad one or two sensors and 6 bolts around the bellhousing and the starter