My 1998 gt recently got back from a long road trip and started running real rough with the check engine light on. The code was a cylinder 4 misfire - so I had all the spark plugs and wires changed and got the full tune up. The car still ran rough, it's slower than a civic at the moment, and now the codes read cylinder 2,3, and 4 misfire along with engine running lean. My gas milage has gone from 23 MPG to around 8, with the occasional backfire, and you can smell unburnt gas when you stop.
Thanks for the help

 

Make sure all wires are ran correctly and that they're plugged into the coil packs right. If everything seems okay, try switching your coil packs and see if the misfire changes. If it doesn't change anything, check to see if your injectors are firing correctly and if you have good fuel pressure. Could be something like an unplugged or bad MAF, bad/wrong gas, bad PCM, or something worse (internal). Usually it's one of the easierthings.

 

Sounds like you may have f*cked your plugwires. Do you have headers? pull the plug wiresoff and inspect them first.

 

if its misfiring and you replaced the plugs.. and its not a coil pack.. im thinking its an injector. ive never heard of a bad injector spreading.. but if you can... pull the injector that was located on the cylinder that gave you the first problem and blow compressed air through it (only real way to clean them). inspect them for damage. another thing you could do... is pull the coil while the motor is running... and that will tell you which coil is bad on which cylinder. good luck.. hope its a cheap fix

 

On the injector note....just check to make sure the sensor is plugged into it first. Jiggle the wire a little too.

You never know...

 

+1 on the injectors, if u smell gas, and ur running lean, sumthins up with the injectors dumping to much fuel.... stock injectors?