Sounds like a good idea. How do I do a full fuel pressure test at highway cruise?

Gottcha
I have been sick for a week and have not done anything to the car in about two. It is currently sitting in the drive with the battery disconnected.

* 2005 Buick Rendezvous 3400 engine
Current symptoms:

* very rough starting

* if you "work" the pedal while starting you can get the car to start with a very rough inconsistent idle.
(While trying to start it sounds like the plug wires are crossed. I have checked the plug wires and they are in the correct order. I have also checked with a spark checker that there is a spark coming from each plug wire. I have not pulled the plugs to check that each plug is generating a spark as I have not done anything that would have changed how the plugs were before the thermostat change when the engine was starting and running normally. If this was a rotary distributor type engine I would get out my timing light and try to adjust the timing. While starting the live data on the timing advance is all over the place on my OBD2 tool.)

* if you can keep the car idling for about a minute the car engine smooths out but races at 3000+ RPMs
(Once it smoothes out it will continue to slowly increase RPMs. I haven't been brave [or stupid] enough to let it get past 3300. Once the engine smooths out at about 3000 RPMs the live data on the OBD2 is showing the timing at 27 degrees)

* Occasionally if I let it run for a minute or so at 3000+ RPMs I get a P0300 code but I have not been able to duplicate that consistently.

* While everything was apart to change the thermostat I sprayed the throttle body and air intake including the MAF sensor with carb cleaner (I did not disassemble the MAF when I did so). Since then I have disassembled the very dirty MAF and sprayed and cleaned it thoroughly with MAF cleaner. I have tested the MAF as well as I can with my multimeter, my OBD2 tool gives me a check that my MAF is working, and I do get live data from the MAF when starting the car. The MAF is now shiny clean, I did not touch any of the wires with anything and as far as I can tell/know it is working correctly.

The only time you touch that pedal while starting is to push it to the floor and hold it. That is only when the engine is flooded. The PCM expects one or the other but not up and down.

It could be a bad IAC maybe.

Well the IAC definitely is not good.

I pulled the IAC (what a pain that was) the plunger was extremely covered with soot. While looking at it, the plunger popped out of the solenoid. The ID threads that the plunger screws in to are deteriorated and would not hold the plunger any more so it is possible that the plunger was stuck in keeping the IAC closed.

I put everything back together including the IAC (without the plunger so the IAC is now always open). I tried starting the car but no luck. It sounds like it is going to start but doesn't. since the IAC plunger is not in the system I did not try pumping the pedal to get it to start.

I have a new IAC on order and it will be here in a few days. I will give another report once I have the new one installed.

Cool, sounds like you're on the right path.

Without the plunger it would probably run lean, and no amount of pressing the accelerator would help that.

The IAC came today so I put it in. No Luck

Hear is a video of trying to start the car:
The first try is with the pedal all the way to the floor. Then we tried a few times without pressing the peddle at all, it would try to start but as soon as we let off the key it would stall. then we tried a few times working the peddle and could not get it to start then either.

After I stopped recording I noticed a smell of gunpowder/fireworks mixed with exhaust, I asked my wife if she smelt it and she said "Yea, there was a big cloud of smoke coming out of the exhaust while I was trying to start the car!" I walked around the back and noticed smoke wafting from the exhaust so I took this second video while trying to start the car again. (my wife was working the peddle.).

It looks like it'* dumping a ton of fuel. What is pressure at? Could have injectors full on.