In park with engine running everything sounds fine and smooth as can be. all fluid levels are good. when i put it in gear it sounds and feels fine. when i start rolling i hear a roar. it doesn't drive funny, it steers like its suppose to, the transmission shifts as its suppose to, there's no jerking, pausing, strain, nothing like that. just a roar. i recently bought new tires and i still have the roar. the service engine light came on yesterday. i cant find anything wrong anywhere. i just got that annoying roar. thank you for your time ,,,,,,,renee dudley

When you say rocky spot, what do you mean? If you mean there were rocks in the roadway, you could have put a small hole in the transmission pan which leaked all the fluid out of it. First thing I would do is check the fluid level on the transmission dipstick and look for leaks on the ground under the car.

You have too much fluid in the transmission. Park on level ground. After a 15 min drive. Leave engine running. Set parking brake. Transmssion in neutral. Check tranny fluid. A cup or more over will cause this. Better to have less than too much. Drain at least a full 1 leter bottle. Go for drive check it again. As above.

First thing I would check is transmission fluid level. The fluid should be checked with engine warm, engine running, in park and good idea to have emergency brake on. You may know this but many people check transmission with engine off and think it is overfilled. I met one a couple months. It happens.

sounds like you have a manual transmission. ?
Worn Clutch plates will give these symptoms
The clutch plates rub together and provide connection between the gear box and the drive shaft if not worn.
Also check the cable for the clutch is not loose and needs a surclip to hold it in at the firewall.
Check if Hydraulic Clutch that there is adequate clutch fluid if low might have leaking clutch master cyclinder

I have experienced this in a car I owned.
Not a lot of fun . Resulted in needing a Tow to repair garage and new clutch was AUD $1200 a couple of years ago.

a car wont roll when in gear

I think you should check the fluid level in the trans since your on a flat spot it sounds like the the pick up tube can't get the fluid in it because the level is low inside so always check on level ground and check it while it's warmed up and engine running in park and I think you'll find the fluid level is low fill it up and park it with card board under it to check for a leak good luck Stephen

Before guessing at transmission problems, check the fluid level (car warmed up, engine running in Park on level ground) and have the PCM scanned for trouble codes FIRST.
1-2 / 2-3 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
Start with that and here is a link for obtaining your DTC codes to your Sonoma. http://www.troublecodes.net/GM/
Thank you for using fixy and good luck

How many miles and how does your transmission fluid look?

Get car ot normal oper. temps and put on level ground. Put trans thru all gears with foot on brake. Put into park, leave running and check level. If level is low, this could be part or all of your problem. If level is fine and trans fluid is not brown or burnt, you have an electronic problem.

If fluid checks ok, let me know if you have a Check engine light on, ABS light, etc.

Hope that helps.

check your transmission fluid with the engine running and gear in park. check the level, color, smell, and feel it. adjust level if needed, if it's black, smells burnt, or you feel small metal like shavings, your tranny is junk.

have ypu checked the fluid level in it? if the fluid level is good, you might want to replace the fluids in it