Well this must be fate, cause I tell ya that I am in the same boat. Nah this aint love.
When Rob83r says diff bush, I believe he is answering to your third point.
It could be your diff bush that is fubar and replacing it normally solves the problem.
However if you are like me, I have replaced the diff bush with a red nolothane bush.
I get the thud alot if I set my shockwork suspension to soft/hard. Cant remwmber which. Did it once and didn't like the sound and didnt do it again.
The second point in regards to the thud, is it coming from the rear, if it is then it deffinately sounds like the diff bush. Even though mine has the nolothane bush, it does thud during gear changes, but not as bad when the factory bush was fubar.
This week I was getting the following error messages coming up:
P0133 - Powertrain
O2 sensor Circuit Slow Response
P1000 -Powertrain
P1260 -Powertrain
I sent a message to Rob and he said it was fine. It has happened twice in the last week.
This past week the car has been doing weird ass sh*t. When coming to a stop and I disengage the clutch, the engine keeps the revs up at about 1500rpm for 2-3 seconds and then it brings it back down to normal. I thought this was to weird.
Now back to where I started. Must be fate because just yesterday I was at a birthday party. When I left the party and got to the first intersection, the car came up with ETC error and then the car stalled.
In regards to the ETC error showing up. I had to turn the key off and wait a couple of seconds and then start the car (guy behind was impatient).
I didn't get to scan the car then. Got home and scanned for codes with the app called torque.
This is what came up:
P1000 - Powertrain
P2105 - Powertrain
Throttle Actuator Control System - Forced engine shutdown
P2110 - Powertrain
Throttle Actuator Control System - Forced Limited RPM.
I am going to have to speak to the tuna first and find out what the go is. No solution from me, but thought I would share my experience.
Is your car tuned? If so have you used the xcal to scan for codes?