Please tell me it's not the transmission

[Valley olds]

What up everyone, I was having some trouble and I thought maybe you could help. Today me and a friend installed a sound system on my alero. Things we had to do included taking the air intake box and tube off, and making a hole on the bottom gromet. We then installed the amp but didnt find the remote on the stock stereo, so we put it direct. When all was said and done, I turned on the car and got the service engine soon light on. A couple hours later, I was going to my friend's house so he could remove the light, on the way, my shifting was really hard. Switching from park to reverse or drive had a real hard shift as well. Also the car turned off at a red light. I looked this up with the search, and it said that the IAT sensor could cause this. Anyone else have suggestions? I dont know if this heps, but my friend got a P0107 code on the computer scanner. He did'nt know what that was though.