please help

whats up people how yall doing......man some of u guys are so lucky to own a g20...i dont have the mone 2 go out and buy and newer g20 which i love so much had to have it..so i had to go out and buy a 1999 salvage g20...its fixed up but i haveget to inspected which is a headache(help)which any ideas..anyway went to the repair shop yesterday 1..because the engine light is on...2...when i turn on the car i have 2 keep my foot and the gas qnd rev it up to keep the car running..which it crazy...anyway the hook up the diagnostic machine but nothing was coming up...no codes or nothing it just keep frezzing and shutting off takeit to infiniti or somewhere where they have a breaker box...he said there something wrong with the computer .......helpppppp