I have a 2006 PT Cruiser. It keeps coding a P304. 4th cylinder misfire. I have replaced plugs, wires, coil, upper and lower intake gaskets. Its still coding and now the ck engine light blinks. Any suggestions. Im now thinking about a new fuel injectore on number 4.

you would need to do a running test. but if its worse with new injector. then it can be the dispack fault. it feeds the spark plugs. have seen some were the unit has leaked. and made like a cement on the shaft that is the inside of it come out and dropped down the shaft. also the rubber will go white like water marks. check them to make sure they are the same if it does look like what ive said change it. they are not dear to replace.

This procedure takes approx 3 hours.You have to remove upper intake manifold and cylinder head cover,in order to replace valve cover gasket.
Its a huge procedure,but can be done easily.

Click the link below and follow step by step details.

http://technoanswers.blogspot.in/2012/06/valve-cover-gasket-removal-guide.html

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This will help.
Thanks.

Check on intake silicon gaskets, upper and lower. About $18 at autozone

could also be a bad coil or ignition wire

Intake manifold gaskets leaking internally.

Very common the intake manifold gaskets leaking. I've replace tons of them. They can **** air internally and cause a misfire.

I would start by having your codes cleared. If a fouled plug was the culprit, the pcm may not have reconized that it was fixed.

Try running a bottle of sea foam through it. You could have a sticking fuel injector.

As a last resort , have a compression test done. A crack in the clyinder head could also cause this issue.

I hope this gets you started :)

They are still looking for a cause because it isnt misfiring right now or because they cant find the cause of the stored misfire codes ?
If it is misfiring right now and they cant figure it out then perhaps you should find new mechanics !
I have seen a lot of bad coils on the PT.
Misfire is usually caused by spark plug wires first, spark plugs 2nd, and coil third.
If it isnt misfiring now, spray down the wires with water. If it misfires after that replace the spark plug wires and spark plugs and try again.
If it still misfires then the problem will likely be the coil.

440 and 441 relate to the evaporative prurge flow system and 303 is a misfire detectec in cylinder 3.

Removing the intake is no prob. on these. Assuming this is a non turbo model, you remove the two bolts holding the egr tube flange at the back of the intake. You will have a couple wire clips you need to dissconect and small vacum hoses that will be easily noticable as you try to move the intake aside, but there is a row of small bolts at the front inbetween the intake rails holding the upper intake to the lower. Seperate the manifold by removing these bolts. it has rubber gaskets that stay right with the manifold you do not need to replace at reassembley. This will allow you to move it far enough to change the plugs. Hope this helps.