Help Needed Now! Failsafe Engine Mode and Check Charging System

2005 Ford Mustang GT. 4.6L Stock

Alright, let me start from the top of the situation. I originally got a P0506 code from autozone , after i changed my battery which was declared dead by the autozone electirc test, and my car kept having idle "problems". So i bought electornic cleaner Cleaned the most of the sensors, took off the front hose to the trottle body and used throttle body cleaner inside with a rag to make sure it was clean. Yay the car ran right. Then we cleared the check engine light and when putting on the positive cable broke the cable end attaching to the battery so i bought a new one and put it on. Now i have a " Failsafe Engine Mode" Followed by "Check Charging System" WTF..... Need help as soon as possible! I dont know much of anything about cars just going off what to do by fourms.....thanks

okay like an idoit forgot to connect the charge cable to battery i did that the check charging system has gone away but the "Failsafe Engine Mode" is Still There......

Found Problem Still Need Help!

I found the problem.....but i need someones help so i can figure out what this part is i need its on the Throttle body and it deals with a pin,spring, and plastic cap. In not knowing what the previous problem was i tried to twist off plastic cap and it broke. Now its my only problem..... Here is a picture i been fourm hunting to correct the problems that i have had but havent been lucky in the diagram section of it to find out the part or if it has to be the entire throttle body ordered.....thanks for the help

2 cables attach to your positive side on battery

2 hours later its an Throttle Idle Adjustment Screw------ Now i just need to find where i can buy one