I am not quite sure what happened

I bought a 03 GXL cruiser 3 1/2 years ago with 70000 kms, it was a MUM bus, I have serviced it every 5000 ks since without fail, it now has 160000ks on the clock.


3 years ago on Frazer Island I let it idle for 2 hours to charge a battery and keep the fridge cold until we gave it a good run the next day, once the battery had charged I gave it some revs and it ran like a charf cutter for about 5 minutes, then it ran fine up until this afternoon.

I did a service on it today, it was close to 5000 ks over but it had not worked hard in that time, it is the first time since I have owned it that the service was late.

I drained the oil replaced the filter, I used the same oil I have used since I bought it, I ran it for a few minutes and then throttled up to see if the oil pressure would lift, as I did so it ran like and old mole and blew heaps of blue smoke, I turned it off then started the process again, this time it had less smoke but still ran like a pig, I repeated the process a few more times, the smoke has now gone but as I throttle up the oil pressure drops and it runs like a pig at mid range revs.

Has anyone come across this before?? has the engine been glazed from the previous owner?? I am stuffed if I know and I have owned a few 1hzj engine in my time.

Thanks in advance.