Good morning,I purchased this truck about six months ago. I got it from a friend that has a tow company and it would not Idle properly. He knew nothing about the vehicle except that it drove fine as long as you kept your foot on the gas and didn't try and let it idie. I was told that I could have it for $500. As is or he would fix it and sell if for $1,800 I bought it as it sat. I took it to another friend who discovered they had drilled a hole on the Catalytic converter. He replaced the catalytic converter, the Oxygen sensors, new battery, plugs, wires and a few other things. After I got the vehicle the CEL came on. The code read system too lean. A lot was happening in both my friends and my lives and long story is we never got it back for a significant amount of time to figure out the problem and being the mentality challenged person I am I kept driving it ( yes even after the CEL started blinking) I am not a mechanic, and my finances were not going that well. By the time it got really bad I started running codes and replacing parts that may or may not have been needed. Up to date In the last Couple of weeks I replaced the plugs and wires, the purge flow valve along with the solenoid and new tubing, next was pcv valve and then the new Catalytic converter and both o2 sensors. Because I blew a hole in the catalytic converter that my friend put in, when that happened I went to inspect it and discovered the wiring for the oxygen sensor wrapped around the driveline and ripped out of the oxygen sensor. I just replaced the idle air control valve and and ran a scan and bank one o2 heater circuit wiring code came up also I found a significant amount of oil in the air intake system I took ei all apart and thoroughly cleaned it all along with the throttle body it was completely caked with gunk and I had to use almost an entire can of carb and throttle body cleaner and wore out a brand new toothbrush scrubbing the buildup.inside the throttle body. I replaced the camshaft position sensor and I have been trying to do research about the wiring for the oxygen sensor but I haven't had much luck finding a wiring harness for that? I am wondering if that could have been damaged when it got caught up on the driveline. While I was replacing the Idle air control valve I also discovered two female wiring connectors that are just hanging without anything plugged into them on the passenger side of the engine compartment one is right above the washer fluid reservoir and the other is between that and the heater core. I have no idea what to do next. The oil in the intake system has me wondering if it has a vacuum leak or worn o rings from what I have read.