I have a 1998 Monte Carlo ls 3.1 with 48,000 miles on it. It been running rough for awhile now. And not showing a check engine light. My friend suggested changing the coil packs. After we replace those it ran ok for about 20 minutes and then it threw a check engine light. We put it on his code reader and it said code p0306 which is a misfire. After that we changed the plugs and wires. While doing so the back side the second plug was super hard to remove and ended up breaking into and smelled of gas really bad. After replacing the plugs and wires it ran worst than before. Could it be a bad fuel injector fuel pump or fuel fitler. ( This was my grandmothers car she never would ever run the gas all the way out if it was on a half of a tank she would go fill it back up when i got it i would run it to empty then refill could some junk from the tank clogged up the pump fitler or injectors.)where should I look next really wanting to get this car running right again.thanks for the help

 

Does his code reader also display live data? That would make troubleshooting much easier.

The one upside is youve got a misfire on one specific cylinder, so its less likely to be something that would impact the whole engine like a pump. Id start by checking the stuff specific to that cylinder- plug, wire, injector, coil pack.

If the other 5 cylinders don't have any misfire counts, then flip flop components one at a time with a good cylinder to see if the misfire moves (indicating you found the bad part) or stays (you haven't).

Given it started running bad right after you touched it, are you sure everything is ok - wire pushed on all the way, wire not damaged, nothing that you unhooked to get to stuff?

As far as the plug that was hard to remove- which cylinder # was it? How did the plug tip look compared to the others?

 

This could be a Vacuum leak too. I have had 2 Monte Carlos that have had a Vacuum leak and it ran really rough too. One time wouldn't hardly start.
Check the Vac line from the intake to the fire wall as it goes towards the master cylinder. might have come loose or could be bad.
Don't run the car out of Gas because the fuel pump needs to remain cool and it does that with fuel in the tank, it could have sucked up some debris because you ran it down.. Your Grandmother was smart!!
If the fuel pump is working you will hear it kick in when you turn the key on. You will get a buzzzzzzzzzzzzzzzzz

 

I think it was the 4th cylinder and the last time i started it after changing the plugs and wires the engine light was flashing

 

Almost all of the time if it ran bad immediately after you touched something, the failure is probably related to what you did.

Maybe something isn't plugged back in all the way, maybe something else popped off / broke while leaning in there to do the job (vac line, wire harness, etc), or maybe you got a bad out of the box component.

I'd retrace your steps first to look for obvious stuff.

If it is something else, I'd take the time to properly test and diagnose it rather than just randomly throwing more parts at it.

 

Now it's reading po300

 

What have you checked since the last posts that we suggested and what have you changed?

It's hard to give much help without some additional info, especially if the misfires are happening all all over. P0300 is one of the broadest codes out there in terms of cause, so you're going to have to give us some kind of diagnostic info to get any useful responses.

 

Well today I had some free time and I went out and started the Monte Carlo and it was running pretty good the engine light was still on. I let it run for awhile and notice I was about out of gas so I took the chance and went to the gas station up the road. As soon as I pulled out of the drive way it died .I started it back up for down the road and notice that the engine light was off and I had more gas in the tank I went ahead and got had anyways and came back home. When i pulled back in the driveway the rpms was jumping and then it died could this be a dirty iac valve

 

If you've checked the suggestions above, maybe try checking the compression (hopefully it is above 0). Your initial problem sounded very similar to what I had once, though yours has significantly fewer miles than mine.