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.
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.
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.
You may need to have it rewired or have it replaced.
piston rings are bad
It depends on whether the distributor has been replaced or removed, and whether they put it back the same way. In any case, #1 is wherever the rotor is pointing when #1 is at TDC of compression cycle.
It is a non serviceable part of the distributor. The distributor has to be replaced.
It's in the distributor. The whole distributor gets replaced when you nneed a new one.
Check the compression in your cylinders
The coil on the 2.5l is in the distributor. To the best of my knowledge it is not serviceable. The distributor must be replaced.
It could be that the distributor was not the problem. Need to know what the code is and what engine you have.