Split liner / head gasket symptoms

Long time no post eh....
I'm fast approaching 7 years of ownership with this 850, it passed it's mot again in August needing two wishbones and no advisories and I'm still very much in love :lovestory yesterday however it decided to test my loyalty and I canny just figure what is wrong with it or what direction to take it...
Travelling home from work as normal, happened upon a tractor and got past as normal 3rd gear 6k while the opportunity was there no problem, few miles down the road traffic had stopped as did I and the car was vibrating and when I could move in wot in 1st and it was misfiring terrible so nursed it home with the misfire and vibration still evident, left it running when I pulled up checked exhaust sounded and smelt normal..... popped the bonnet all looked normal reved lightly seemed fine rev hard it misfires, water water a little low but not below min and oil level fine with normal moisture on dips tickets but pcs was due to be changed in the coming weeks so I left it....
Checked water before I left for work it hadn't moved started it up normal sounding no misfire, tootled down the road and had slight misfire which got noticeably worse once warm, got to work and pulled each plug lead, each injector lead and maf plug off and none made a difference and the top radiator hose was pressurised..... I did get the cap off and it gave a big gurgle but no oil evident in there and no obvious water on dipstick.... drive home similar misfire, vibration but full boost and no signs of smoke.

So if you've managed to read through all that, Google has came up with no exact match so my train of thought is...
Split liner
Head gasket
Bent rod
Snapped cam

but I'm stumped and I don't just know which direction to go now so any input at this point is helpful, by the way it's still the same 95 t5 manual no engine mods bar a 16t cheers craig

Get it compression tested mate and read the codes.

Could be anything but a compression test will let you know if the headgasket is leaking.

misfire and vibration could be coincidental and be 2 separate things, recently had a nasty vibration up front on Gul, to find the front engine mount had destroyed itself (the one under the crank pulley). As for the misfire, boost leak is springing to mind, as it idles ok and starts to miss when rev'd up or under load conditions, may just be a corroded clip or a perished hose, we had similar on the Gul and she had blown a hose back a bit on the top intercooler hose spigot, V70R had a lower intercooler hose clip rot through and blow the hose off, that was a real pain, as the ME7 didn't like that at all and you struggled to keep it running, even at idle let alone trying to move off. Hope that helps and good to see you back here Craig.

Just a little update, after much deliberation and head scratching and miles since (I've gotta get to work), oil use is unchanged water is unchanged, outside of the car the engine is as sweet as ever, still no unusual smoking no hint of misfire and driving its still got plenty of power.... It does, however, have a vibration on tick over felt all over the car and whilst driving the vibration is horrific at 4k, if I drive very cautiously it's basically as it should be but if I use any boost up the revs it doesn't want to change up the gears.....

I'm pretty confident now that the trouble I'm experiencing is clutch and/or gearbox input shaft, when I was overtaking the car and changed from 3rd to 4th it seemed like I'd not pressed the clutch properly and the gears missed, where I think back now and I depressed the clutch again and got 4th I musta either buggered something or something gave up right then....
So I've a na 20v gearbox here to go in I just gotta save now for the clutch kit etc

Is it a single mass flywheel or a dual mass?

I would hope its a single mass, it should be given its age but I don't know for certain... The dude I had it off did change the clutch not long before I had it but I don't remember he saying about a dual mass