I have a 2001 impala 3.8 engine, when i got it used in 2009 it was almost perfect, the only problem it had was it didnt always start on time sometimes i would have to let the car sit for ten fifteen min then it would start. then it started doing that more often. now its 2012 my car has maybe 110-115,000 miles on it. in Dec. 0f 2011 my car stopped running, i thought it was an alternator, changed that still wouldn't start, changed the fuel pump put on a brand new one with filter, changed the ignition, my horn stopped working, and my inside lights come on while i'm driving, my main thing is why after putting all these new parts on my car it still won't start, a mechanic told me it thinks its being stole and is in theft mode, how do you get it out i need my car, my engine and transmission are in great condition, and i love my car, can someone please tell me what to do, i spent 700 dollars in two days on what might be the problem. please tell me what i s wrong so i can hopefully fix the problem!!!!!! please and thank you

well after reading about all of the Chevy impala problems i dont feel so alone , i went to a mechanics shop and had it diagnosed and they gave me four things wrong with my car , 2 sensors my catalytic converter and my gas cap , now that i have replaced all of them they failed to tell me that my computer chip has to be reprogrammed because my anti theft security on the car will not let it start, now they cant do it and now i have to send it to the dealer after spending six hundred dollars.now im going to have to deal with these ass holes because there is no one else who can reset the vehicle.im at there mercy , and to think i didnt even get a kiss, thanks Chevy , obama needs to let your asses go bankrupt .