I have a 1999 Chevrolet Suburban C1500. I had a check engine light but the vehicle ran great. I had it checked and was told the code was for 4 bad o2 sensors. I decided to replace them. My reason being if I had a more serious problem arise I wouldn't know it because the check engine light was already on. So I replaced all 4 o2 sensors. The first drive after swapping out the sensors I knew something was wrong. Low power, engine started missing and the parking break and abs lights where going off and on. I was only able to drive about 20 feet before returning to my place. I put the old o2 sensors back it with no change. Starting the engine the rpm's went up and down several times before leveling out. Went for a drive and it was a bit better but still had what felt like a miss. The next day I started the engine and had same rpm issue. I decided to replace the cam position sensor. First startup after that was perfect. Went for a drive and it was better then before but still had what felt like a miss. The next day the rpm issue returned and the engine ran so bad i couldn't get it out of my driveway. I then replaced the air idle control valve. First start after that was good. She even ran a bit better. Still the miss but drivable. I drove about 1 mile to a friends house. I made it there with only slight issue with the miss. On the way back the engine started with the up and down idle and After the parking break and ads light started going on and off again. I have had someone come out with a scan tool. He found the o2 error as well as a bad cam position sensor error code. He said it was showing an intermittent cam position sensor error. So the next day I replaced it again with a new one. Same problem. I have no idea what is going on with it. I'm thinking it feels like a timing issue. But it ran great before I replaced the o2 sensors. I'm also thinking it might be the computer is going nutz. As the tech that came to my house had trouble running a complete scan. Has anyone had this problem? Is my Chevrolet possessed? This is my daily driver, or was. My HHR SS overheated and my wife seized the engine in my Ram. I really need to get this working and would greatly appreciate any information anyone might have. Thank you in advance.

 

Just to add a little more information. When I bought the Suburban about a year ago the ignition switch wouldn't start the engine. The previous owner would jump the engine at the inside fuse box. I added a momentarily button connected directly to the starter. I would turn the key to the on position and use the button to start the engine. I assumed it was a problem with the key and serenity system. Back to the problem at hand. Immediately after installing the 4 new o2 sensors, the ignition started working. Right after I swapped the sensors I went to start the engine and it started as soon as I turnd the key to start. Something it had never done since I bought it. I reinstalled the old o2 sensors and the key is still working. I have no idea if that it related to my current situation, but I thought it worth mentioning. I am going to try and pick up a different ecm and see if that might be my problem while I await a response from the community.