Stop throwing money at the car and correctly diagnose your problems.
Diagnostic Trouble Codes. Hundreds of sensors and functions are monitored by your car's built-in code reader/scanner. Have it read at any parts store (scanned), use the below link to decipher all found trouble codes and post it all here.
Welcome to CF !!! I changed the title of your thread to better reflect your problems.
OBDII/EOBD diagnostic code definition. More than 18000 codes for all autos. Trouble codes description for GM
obdii.pro
Codes read out as a capital letter, four digits, maybe a letter suffix.
Example: P 0300 C = Powertrain misfire detected Current