Ok. So, this took about a week to rip my heart out. I just gave my car an oil change and took off down the road. Everything was running fine and then my car stalls for a second I didn't think too much of it. Then, a second time this happens and I am started to get concerned but no check engine light. It's also an inconsistent problem. The next day I am out delivering pizzas and as I am driving I hear a pop then my idle revs high. The car will now stall out if car is over 3,000rpm. I have to shift at or before or the car stalls. Runs like crap now like it's missin'.

Next day. I get out to the car and it won't even start now. Get the code reader out and it reads an immobilizer code on the ECU. What's next?

What are the common causes for the immobilizer to be tripped?