Toyota Repair: Idle speed Tac Bobbing, matrix xrs, toyota matrix

Question
03 Toyota Matrix XRS 6sp.56K+ml. I just got the car back from the Dealer after having the starter replaced and tranny worked on. They dropped my car off a floor jack and had to repaint the front bumper. Now the Car wants to idle at 1.5-2.1 rpm, cold or warm, it cant make up its mind.  When you shift there seems to be a lot of drag, the tack drops real fast sometimes to .4 rpm and if you keep the shifter in neutral the tack bobs up and down like a yoyo. I took the car back to the dealer and the code was P0505 they reset the ECU and told me to call for an appt. if the ck. eng. light comes back on. I had a ck. eng. light about a year ago with the same code. The Dealer replaced the cat. and no more ck. eng. light, until now. Could they have messed something up when they dropped my car or do I need to clean the TB, ISC, IACV, and MAF to see if that fixes the problem? And is STP throttle body air intake cleaner ok. Quite frankly I'm afraid they are going to tell me this problem is unrelated to what they did and I need to replace one of these expensive parts. I don't know if any these parts are still covered under warranty. I bought this car used a year ago and have had nothing but problems since.  

Answer
The idle fluctuation and the PO505 code can be remedied by removing the intake air hose from the throttle body and then cleaning the throttle body with a throttle body cleaner using a brush, cleaning the gum and carbon deposits inside the throttle bore fixes this problem, I have done a few of these with very good results and yes, it's unrelated to what they did so just have this done to take care of the idle problem.