The car has 149,000 miles. I have only owned it for roughly 1000 miles. Have not checked the plugs and do not have a way to check fuel pressure. None of the mechanics have mentioned that. I have noticed that it seems to get worse as the amount of fuel in the tank decreases.

Ah okay.

Fuel pressure needs to be checked. Especially with the lower-is-worse symptom.

If you don't know that it has good plugs, I'd look into that next.

The car produced a code yesterday. PO171, P159, 53, 00, 15, 99. I am not good with the reader but I also was able to get a bit of additional information as well.

Absolute Throttle Position 19.22 (red)
Manifold Pressure 4.35
Long Term Fuel Trim (bank1) 18.75%
Short Term Fuel Trim (bank 1)-3.91
Short Term Fuel Trim B1S1 -4.69
Short Term Fuel Trim B1S2 99.22 (red)

Dont know if this is helpful but let me know if this means anything. Thanks

Check fuel pressure. It'* lean.

Yup, fuel pressure. I'm amazed the shops you've taken it to haven't done this already.

Do you have any suggestion as to what could be causing the fuel pressure problem? Fuel Pump possibly?

Yes fuel pump assembly. The fuel psi test is required to see if it is within specifications or not.

Yes, fuel pump is likely. Fuel filter maybe (definitely replace if you replace the fuel pump).

Problem solved. After much research and trial and error, I replaced the engine temperature sensor. Apparently, the sending unit was sending incorrect data to the computer and causing the computer to adjust the fuel mixture incorrectly. Either too lean or too much which caused the smell of gasoline from time to time. The end results a $17 part and 15 minutes of labor corrected the problem. Thanks for everyone'* help

Nice!

How did you narrow down to that?