Wont' boost EGTs up out of ideas?

[10G]

Sorry I've reposted this as I'm out of ideas and need some help if possible.

So something's not quite right.

I'm just going to dump all my observations here, it may mean something to someone with more experience.

About 2 weeks back more than usual oil began coming through the catch can, I've been trialling letting it vent to atmosphere post catch can, not been having problems, then noticed one morning I had a small pool of oil on the floor & the catch can barely had anything in it.

Next, this 'pinging' / gear lash noise increased, I am now hearing it when I didn't ever hear it before.

This week EGT's have gone up by 60 - 80 degrees.

I've noticed the exhaust seems to be noisier, more drone coming into the cabin.

Fuel usage has increased.

Boost always sat at 15, dropped when off the accelerator, but almost always sat at 15, now it's sitting at around 5-6, it does go up when you put your put your foot down but hardly gets above 12.

Coming home tonight, in 4th at about 70kmh up a very slight rise, put my foot to the floor. Boost at 4, speed increased marginally, boost stayed at 4 didn't budge.

I've also noticed that it'll pull ok in 3rd, but when I shift into 4th it just dies.

This is intermittant as well.

138,000ks, ZD30, dawse & needle valves, EGR block, catch can, 3" exhaust.

Would it be any use to remove power to the ecu to reset it?

I'm thinking a vacuum leak??????