Gabriel Thor

I bought the bike on Sunday, Monday i got it taxed and insured to ride back home 286 miles away. i rode back no problem and stooped at 2 towns for rest plus one more time for fuel.
bike was fine this whole week even got up to just over 130mph on the motorway with no issues whatsoever and everything running smoothly. the night before last night i headed home from work about a 2 mile ride and gave it some abrupt gas and hit the redline in 2nd gear for about a second or 2 before shifting to third gear and then braking to stop at the lights as they just turned red, after setting off from the lights i gave it gas and once it passed roughly 5000rpm i started to hear and feel an odd vibration plus the bike was not pulling and running on 1 piston. Got home and bike was happy revving to the redline and idling no problem whilst not in gear or with the clutch pulled.
Yesterday morning i got on it to go to work and it started fine, warmed it up for a few mins as its been quite cold these days and rode to work with no issues at all, as if the other day never happened.
today i went to start it and it seemed like the battery was dead so i jumped it with a neighbour and it fired right up, i let it warm up and rode to work with no issues apart from the idle being a bit higher than usual at around 2500rpm. at the main road i gave it some gas and pulled fine, after that i went to overtake and felt the weird issue again at about 7000rpm and after that at around 5000. on the way home from work the idle was normal for a few minutes until i hit traffic and then again it was higher than normal and the bike had no power almost felt like it was only running on 1 piston again and was just not pulling right.

strange thin is when the bike is idling both pistons are running fine, once you give it some gas you can feel one of them not working and the vibration that comes with it.

bike is a stock 02 SV650S, been sitting for a while before i bought it.

any help as to what could be at fault is greatly appreciated