If that's a definite difference, starting looking at everything related to cylinder 5
Try using a different plug lead.
Check the condition of the spark plug. Post a pic of the tip of the plug
Try a new spark plug
Check the injector no.5 is getting a signal, or use a stethoscope to listen to the...
When you check timing, did you open the OBD diagnostic port and put a jumper between the two terminals? (I think TE & E1)
if you don't do this, the ECU will adjust the timing.
Once you have jumpered the two terminals, then set timing. Factory spec is 3⁰, but you can go up to 7-10⁰.
Mine runs...