loss of top end speed

[dracutaco]

i don't know for sure but her is what i have for info.
05 rx1 on radar i run 112 (last year) dream meter 123
this year 105 on dream meter conditions were 2" hard pack on ice
when i got home yesterday i opened the hood and was going to clean carbs when i started to take off cable for choke i thought i saw the choke move,almost like the cable was pulled?
i also noticed light show under hood from 1 of the cylinders, i took the plug wires off and removed the spark plugs, hwat i noticed was a grove had worn into the thread on top of the spark plug and this was making the plug wire move. i replaced the plugs today and that took care of the light show and loose wire problem but i was wondering if this was normal wear?
any help on spped would be appreciated

 

[grader]

remove all coils and clean with brake clean or similar solvent to remove carbon buildup. the slot on the top of the plug is normal wear. top speed is affected by hundreds of different things, including arcing coils.