Need to know what the question is.
the service engine light is on due to the fact that there is a problem with your truck, this is confirmed by the way your truck is running. you need to get a engine diagnostic check at an auto shop. may just need a tune-up, or the truck has a bad sensor, or engine woes.
The engine type will vary from truck sonoma to sonoma, some may have a 1.9L, 2.0L, 2.2L, or 2.5L I4, or 2.8L, 4.3L, 4.3L Vortec V6.
If you have another light that says Check Engine, then the Service Engine Soon light means to change the oil/filter or perform some other maintenance item as listed in your owner's manual. You will see the other light when you turn on the ignition. If however there is no Check Engine light, this light means there is a problem with the emissions system.
use a code scanner!
The proper way is with a scan tool after repairing the cause of the code that turned the light on. A batterydisconnect may also clear it.
There is something not right with the engine.
http://wiki.answers.com/Q/What_could_be_the_problem_when_the_dome_light_for_a_1995_GMC_Sonoma_stays_on_even_when_truck_is_off"
With an OBD2 scanner.
That depends entirely on the reason why the check engine light is on.
To find out why its on you'll need to either take it to a dealership or run a tuner on it and run a diagnostic check on the truck.
where is the iat sensor located on a 2003 gmc sonoma truck
GMC Sonoma