Blue Smoke at Startup; Oil on Plugs

Ok, so I have a 1999 Taco with 3RZ and 235k on the clock. It's been running fine but the past couple days I get blue smoke on startup, and it sounds like the engine isn't firing on all four. Idle is low and lopey but it cleans up after about 5-8 seconds and the truck seems to run fine after that.
I just used the truck to move and it was hauling a lot in a trailer for several hundred miles. During the trip the truck developed an exhaust leak where the manifold meets the downpipe. That's probably not related but thought I'd mention anyway.

There was some light, fluffy oil fouling deposits on the first cylinder plug. Here's a photo of the plugs; 1st cylinder to the far left, 4th cylinder to the right (sorry for the quality):

 

Time to replace the plugs and replace that part where you have an exhaust leak.

You have 235K on the clock. With that much mileage it wouldn't surprise me if your oil control rings are shot and you are now burning oil. Seriously.

 

Plugs are new, I have maybe 2000 miles on them. I'll look in to the oil control rings, thanks.

 

Compression and leakdown test will isolate the problem to rings or head.

Smoke at startup that ends points to valve seals or guides.

 

Very helpful, thanks.