[Aphotodog]

I am a new member after purchasing a 2000 Boxster S with 135,500 miles. I had the CEL come on and took it to AutoZone to find the codes. They were P0507 idle air control system RPM higher than expected, P1128 02S range 2 cyl. 1-3, P1130 range 2 cyl. 4-6, P1126 O2S sensing range 1 cyl. 4-6. A friend told me to check for vacuum leaks. I found the tube fron the air cleaner was not attached. I pulled the TB and using throttle body cleaner. It was pretty dirty having air coming straight into it with no filter. I also cleaned the MAF with CRC's product. I took out and cleaned the K&N filter that a previous owner installed after removing the stock air filter and housin (darn it). Reassembled it all, turned the key to on and waited a full minute, turned switch to off, waited 10 secs and cranked it up. Seemed fine while it idled. CEL was still on. I took a shower then cranked it up to run 5 miles to the grocery. There is a knocking and unstable idle. It runs strong when above 2000 rpm. Pull up to a stop, idle drops to 700 and seems like about to stall. Thing was running great before I did all this but was idling at about 1100 rpm. I disconnected the battery to clear CEL which is now off. Still pulsing idle and knocking when I fired it back up. What have I done wrong? Thanks for any advice.