Yeah it's got SAI. I've already ordered new gaskets and head bolts. I'm going to tear into it this weekend and will report back. I'm stocked up on beer and rum. Happy Father's Day to me!

 

Ah. My only SAI experience is removing it from an engine. We will be celebrating Father's day in similar fashion.

 

UPDATE: head gaskets were in good shape. No pistons were 'steam cleaned'. I've got it all back together and it seems to be running worse. Rough low idle that. The SES light flashes sometimes when the engine is vibrating. I'm getting misfires on 3, 5, 8. I watched the live data on my scan tool and when the SES light is flashing, it's reporting an 'OL-FAULT' on fuel system 1 and 2. When the SES light stops flashing, fuel system 1 and 2 go to 'OL' and things seem to smooth out except for a low rough idle.

What's 'OL-FAULT' mean? Fuel pump? ECU? MAF? I've cleaned and tested all the injectors and put new filter baskets, o-rings, o-ring retainers on them. No leaks. Valves looked good. Very minimal carbon build up. The internals were clean and in good shape. Lifters and rods were in good shape, clean and smooth. I've hunted around with my propane torch and can't find any leaks in the vacuum lines. New plugs, wires, coils. I'm stumped.

 

I was chasing a similar problem, which was the result of multiple issues. You have done the hard parts. I suggest you look at the easy parts as well.
-check the ground wires, you should have at least one running from the engine block to the fire wall. Mine is attached to a valve cover bolt on the drivers side.
-check the MAF, if it's not working properly it will generate all sorts of issues with the fuel mix.
-check the knock sensors and their wiring. A lot of people monkey with these, apparently there was some advice out there on how to alter them to improve gas mileage.
-check the crank sensor, again if it's faulty the engine won't run properly.
-check the fuel cap, believe it or not, it can generate all sorts of problems
-finally, make sure you have a good strong battery and alternator output. Both of these cause the engine to malfunction because of low voltage and circuit failures across all of the sensors.

My issues turned out to be a combination of all of the above. It was neither cheap, nor quick to fix, you just have to keep after it. But, seriously, the most simple things can create all sort of issues, and before you pull out the fuel pump you should try the easy things, if you haven't already.

Good luck!

 

OL means open loop. It should only be in open loop when the engine is cold and when you're past a certain throttle position. (And of course when there's a fault!)
It just means that the ECU is not using data from the oxygen sensors.

 

Should read or when you're past a certain throttle position.
......

 

UPDATE: I tried a generic remanufactured MAF. It was the only one in stock quickly accessible. It made no difference. Do you think I should try an OEM MAF or replace the ECU? The fuel trims vary greatly as you can see. I'm still seeing misfires on 5 and 8 when I hit the throttle. It's idling pretty rough too.

Here's a vid of my live data.
https://onedrive.live.com/embed?cid=...CvaXJnROMPwgAw

FWIW I also tried it with the MAF unplugged and got the exactly same behavior. I think I'm going after the ECU next.

 

Those fuel trims are doing some weird things!
I would do a leak down test. I just had a very similar problem on a Hummer H3. One cylinder was showing a misfire and it had weird looking fuel trims. The valves in all five cylinders were leaking, but it still drove completely normal.

 

Turns out that bolt did more damage than I thought. Failed compression on #5. Bent valve.

 

That's what I thought it looked like. That sucks! Still better than a cracked block though!