piston rings are bad
You distributor cap and rotor should also be replaced. If still no spark. check the compression on the low cylinders to see if you have good compression.
When you replaced the plugs, did you check the compression? Did any of the plugs look different than the others? Low compression in one cylinder can cause misfiring. But then, so can a faulty distributor cap.
Check the compression in your cylinders
low compression on 2 cyclenders ALT ANSWER: You have two cylinders swaped on the cap. I did it to mine. Try swaping 1 & 3.
On the 4 cylinders it is on the top center of the engine. On the 2.5L V6 it is built inside the distributor and is not servicable, the whole distributor has to be replaced.
If there is NO compression on any of the cylinders, you've probably slipped the timing belt/chain. Just knowing that there is no compression is insufficient information to make a decision about replacing the engine. You COULD need to have the engine rebuilt, or it's possible that a valve "kissed" a piston and the engine is toast. Or... it could be something else. If it's just low compression in one or two cylinders, it could even be caused by burned or sticking valves.
Check the firing order which is 1-3-4-2 , if it is correct you may need to have a wet and dry compression test to check the condition of the valves, rings etc.
Run a compression test. If only one cylinder has low compression, it's probably a damaged valve or pushrod. If the compression is low in all cylinders the cam is probably not timed correctly.
verify that the engine is timed properly if that's ok check your compression and vacuum
There is no "chip" that can be replaced in the distributor, it is serviced as a unit. There is no chip in the distributor cap.
They can be replaced, avoiding the necessity to be 'bored out' .
You may need to have it rewired or have it replaced.