New 03 Centennial Gt Owner Here

Hey guys i just bought my self a 03 centennial gt 4.6 Im 17 and worked hard to save up for it and well its giving me some trouble it feels so under powered idk why it drops its idle to the point where it alnost dies and then jumps to aroung 1k or 900 RPMs at idle i did some work on it a while ago i swaped out my itake manifold noticed the tips of my injectors are craking i also have a BBK CAI and a 70mm Throttle body but ive never seen a throttle body like it on a mustang it fits fine but its weird idk what to do its really slow compared to my friends 98 gt 4.6 another issue is my clutch keeps dissajusting its self when i eather Give it gass or sometimes its just ramdom idk what to do excuse my ranting but hope some of you more experiensed mustang owners have dealed with an issue like mines