head gasket problems

In april i bought a 91 cavalier at a used B lot dealer this car has giving me problems engine light comes on. just last week it needed a crank sensor rod put on the mechanic put it on the computer that the only problems came up then couple days later the engine came on it sputters at a light in stall i keep turning the car on again to it stops sputtering and drives rest of the day with no problems and another problem it need head gasket i can't afford to get it fix i don't know that the reason check engine light comes on , and i heard about GM doing a silent recall on head gasket I don't know this car been throught the recall and do i need go to gm have them fix it free i just bought this car in april it has 162000 miles in the dealer told me it was a good runing car and no problems i test drove it before buying.
I don't know what to do about this car.