Why do I get check engine,reduced engine power and traction control li

Why do I get check engine,reduced engine power and traction control li I seem to get this problem more often when it's hot out. When I start my 2005 equinox sometimes it runs rough and I get my check engine,reduced engine power and traction control lights on. I've replaced my pedal sensor because a mechanic told me he thought that was the problem but I still intermittently get the same problem.