Hi I have a 2002 chevy cavalier z24 that just started running rough. On my 65 mile way to work I noticed that at a low rpm it really misses a lot. The car starts shaking and everything. This has happened to me before and I replaced the ignition coil, housing, plugs boots, and its fine. Well this time it was a lot worse, but I still figure that it might be the problem. On the way home ten miles from home, it starts running on, well, it sounds like two or three cylenders. The exhaust sounds bad the whole thing rattles. I didn't know what else to do so I had the old ignition coil from 07' the last time that it ran bad, not nearly as bad, still totally drivable then. I put them on the motor and also I put on new plugs. Nothing changed. Any advice would be very appriciated:)

Sounds like timing chain slap meaning needs new timing chain or belt dependinding on the car.
Could be pluged fuel filter ,dirty intake,theirs a lot of possibilities could be a malfunction in the computer.
Take it to any autozone store and they will do a computer analysis and tell you by the code what is wrong.
Could be as simple as bad gas.
\try putting a can of dry gas/injector cleaner in it and se if that helps.

Thank you very much willy. I put a container of heat the red bottle, and a can or seafoam. The only problem I really don't want to run the car that rough. Nearest auto zone is 50 miles away. If you could, would it be possible for you or someone else to define timing chain slap, and everyone please say "please Lord dont let it be a timing chain." And if it is, how does a guy change it. That's a part that I really don't want to mess with, but if I have to I have to. But if it is something else that would be better. :) thanks samuel

. Check for codes.
. Change fuel filter.
. Ensure spark plugs are the same plugs that came in the car.
. Change Ignition Control Module--this may be the source of the problem:

http://shop.advanceautoparts.com/pro...pe=194&PTSet=A

Timing chains and timing belts control the exact time the plug fires.
The timing chain has to be tight with no back and forth play to insure a exact fire on all cylinders.
If you have timing slap at 8 degrees before top dead center and it has this slap the timing can very between 7 degrees and 9 degrees throwing the timing into various patterns being not a true 8 degrees on all cylinders .
This will make the engine run real ruff.
I had a engine that did not want to run right after changing plugs and all that easy repair stuff but I then decided to get in deaper and changed the timing chain.
It ran great afterwards tilll I blew up the tranny anyway.
I'm not a what they called qulified mechanic I'm just a back yard mech with 40 years of messing with these things and can pretty much tell by explanation what is wrong but don't instantly agree that I am right I could be wrong.
If you have any auto parts places around where you live I would check with them and see if they can do the computer code check for you to verify that this might be the problem.
All they will do is hook a little computer to the connection under your steering column and get the codes for any problems the car might have and look them up for the explanation.it only takes about 20 minutes.
Most service stations do this also though they may charge for it .
A lot of places do it for free cause its not a expensive process .
This will ensure you are going in the right direction
These cars also have a key you can get that plugs into this connection and through a certain process for that car will flash a light on your dash giving you the codes for the problems.
I got this key for free at autozone and they even showed me how to do it.

Thanks guys, I will check the codes. And let you all know the results. Will be a few days.
Thanks samuel

Did you clean throttle intake and MAF sensor? EGR valve? These things often get overlooked.

I will try that. Thanks.:)

well I finally got to throuth a scanner on it. And I came up with a couple of trouble codes. A p0300 Random multiple cylinder misfire detected, and a p0440 evaporative emissions control system malfunction. Any thoughts would be appriciated.
thanks

Did you replace the ignition control module when you did the housing, boots & plugs?

Also, I recommend staying with GM parts for the housing, as the aftermarket ones never seem to come to OE specs; they always end up going bad very quickly.