I have a 1998 Mercury Grand Marquis rough idle, smelling gas first few minutes after I start my car. My car is also flashing engine light sporadically and losing acceleration.I recently changed spark plugs, 4 new boots and one coil. The car also wants to stall when I back out of parking spot and has stalled a few times at stop light.

SOURCE: intermittant stalls & rough idle

i would say maf 2

SOURCE: Subaru stalls while driving, and idling

check the cam and crank position sensor making sure that there is no metallic deris

SOURCE: My 2003 subaru forester idle very rough. if you

1) Check all the vacuum hoses for a leak in the rubber hose or a hose that isn't connected. Vacuum leaks cause motors to shake and stumble on acceleration.
2) There's a plastic T connection on the back side of the engine behind and under the air cleaner box. That T connector joins together three air hoses of different sizes and is prone to breaking from heat stress. Only a Subaru dealer will have this part.
3) Even though the spark plug wires are new, you may have a bad one. Don't waste your money on cheap parts; they cost more in the long run.
Good luck!

SOURCE: 1998 subaru forester runs rough when it rains.

Check the cap and rotor for internal carbon tracking or, just change them. Also, take a look at the coil when its dark and rainy and see if there is any arcing where the coil wire goes into it.

SOURCE: Engine stalls while driving and sometimes while idling.

The stalling problem could be caused by a faulty mass airflow sensor. That is the PO100 code. The other code is for the engine coolant temperature sensor. Go to the autozone website at autozone .com and register your vehicle. It's free and you will have access to an online repair manual. The procedures for testing the MAF sensor is outlined there. Hope this helps and you find a resolution to your problem. Best wishes.