1998 Ford Escort Shuttering

I have a 1998 Ford Escort that recently began shuttering (mainly at idle, but also occasionally while driving). When stopped, the shuttering seems better when I put it into neutral, but the car often dies when shifted into reverse.

The check engine light came on, with a cylinder 1 misfire code. I then replaced the spark plugs and the wire for cylinder 1, as well as the fuel filter; this made the car run slightly better temporarily, but the code still came back on.

The car is also getting horrible gas mileage (down from 25 to ~15). I can also smell gasoline sometimes.

Any help?

Shuttering?..do you mean stuttering?

feels like the idle is dropping, or the engine is not getting enough fuel; the car sort of shakes when this is happening, and sometimes just dies; but starts again fine.

The most likely problem, and easiest to fix, is a vacuum leak. Inspect your vacuum hoses for cracks and replace as necessary. If you use a length of rubber hose as a listening device it may help to locate a leak... you should find a hissing sound.
While vacuum leaks are easy to fix- they are not always easy to find.

If you have trouble finding one, try unplugging the hoses from the vacuum port on top of the manifold and plug them with a cap. If the engine continues with the same behavior then the leak may be on the manifold (assuming it is in fact a leak).
If the car appears to run smooth then replace the vacuum lines one at a time and see if you can isolate which system the leak is in- then follow that hose and inspect each component in its path.

my car = same type of stuttering...

try finding the pcv (located on front of engine near the thermostat)
check for broken / cracked rubber elbow on pcv (and potentially replace the $5 pcv & $5 elbow with parts from autozone)
follow pcv hose towards firewall... (remove the hose between air cleaner & throttle body to see where the pcv hose goes... reach down from the top side of engine-- with your face near battery and reaching towards passenger side of car) see if you feel hole in bottom side of pcv hose elbow near firewall -- this was the problem area for my escort

if the firewall side elbow is the issue, you'll need to pull off a difficult clamp to get the elbow off and the $5 "STOP!" brand chrysler pcv elbow (small diameter one side, larger diameter other side) supposedly fits-- mine was sloppy loose on the hose side & needed some sealing tape assistance :)

hope yours is as easy as mine...