Wow I dont know what to say about that. I feel bad reading it. As for the issue its only one of a million things it could be. Ive heard things like cam sensors to throttle body. Best plan is take it in and have them plug it into the computer and get you a read out. I cant give a best guess on price because I've never heard of that happening, best of luck though!

 

You've gone into "limp mode" which is to protect the engine. Search the forum for SES, VDC, SLIP, limp and you will get lots of threads with lots of reading. Most of which adds up to: get 'er to the shop to have the codes read.

 

Same thing happened to me in my 05 sedan except mine had over 185000 Kms on it! I took mine back to the KIA dealership where I bought it (you read that right!) and they fixed it on their dime! Turns out ita dirty throttle body gate. Just get your G35 check out at a shop and it'll be fine.