New to rc nitro

[hokuspokus74]

can anyone help me,i got my 3 boys himoto nitro cars,i am having problems with them i cant get one started,and the second one starts for a few seconds then stalls how can i stop it stalling on the break-in stage,and the same for the first one also,am not going to touch the third one to see if i can get these to running and engine broke in.

cheers