I have a 2004 Pontiac Grand Am with a 3.4L engine. When I start my car after it has been sitting for a while, especially in the morning, the engine shutters making the car shake when it is put into Reverse and Drive. Plus a horrible gas smell come from the hood and into the heating vents. So to alleviate the shaking I let the car run for several minutes which in turn makes the gas smell worse. The smell continues to get worse when the car is stopped at a alight or stop sign. to eventually go away as the car heats up. The check engine light blinks with the shaking then disappears but eventually stayed on with a cylinder misfire code. I took it to a shop who told me that was the head gaskets, a convenient $2400 repair so I’m pretty sure they are trying to rip me off. Any help would be greatly appreciated
You do have a bad cold misfire which can easily account for the fuel smell. There is no single reason that this could happen. There are lots of reasons it can happen. A head gasket problem is one of them.
What is the basis for their diagnosis of head gasket? I.e. you don’t guess about head gaskets, you test things to find out. What kind of a shop was this? A corporate “auto care” chain perhaps? Or a local, independent mechanic?
The error codes come in a very specific format like - “P1234.” There can be multiple error codes present, and there are multiple misfire codes. What was/were the exact, specific code(s) that were read?
Have you checked your oil? What does it look like? Have you been losing any coolant? Has the engine temp been behaving normally?
How many miles are on the car? How old are the spark plugs and wires? Fuel & air filters?
Have the manifold gaskets ever been done on this car?
Well, the first thing that I would do is to bring the car up to date with maintenance, as that could resolve a misfire situation. While there could well be other causes, you should first eliminate the biggest suspects–such as bad spark plugs and plug wires before moving on to anything more expensive.
However, resolving a misfire–whether by simple maintenance or by actual repairs–does not necessarily eliminate the possibility of head gasket (or–more likely–intake manifold gasket) problems. Continuing to drive a car that has a flashing/blinking CEL (even if it is only a part-time flashing/blinking) is doing more damage to the engine each time that it appears, so you really need to deal with the misfire promptly.
Overall, it sounds to me like this car has been badly maintained, but if I am wrong, please feel free to correct me.
Diagnosing a problem before bringing a car up to date with basic maintenance is going to be more costly and more time-consuming in the long run. First–maintenance, then–doing diagnosis again if the symptoms persist after maintenance, and finally–repairs.