Cadillac Repair: repair, head gasket, vacuum leak

Question
i had a guy fix my 1998 Seville sls he put a head gasket on it and he said it has to reboot for the car to run right because the brake petal is hard to move and when you hit the gas it 's not getting any power

Answer
Reboot my BUTT. From what you describe about the brake pedal being hard to depress and the engine not running smooth, This sounds exactly like a vacuum leak most likely due to an intake manifold leak of which he would have had to remove and or reposition to replace the head gasket.

Also you NEVER EVER replace ONE head gasket, You ALWAYS replace BOTH.

FYI: There is NO reboot sequence and never has for this year vehicle.