mzr310

i am having issues with my truck. it was acting like a timing issue with the backfiring and spitting. it was only doing it every now and again but now it does it every time i drive it. i checked the codes and it is giving me 24 and 31. it was throwing in another but i replaced the pick up coil and now no code for that but still runs like crap. to keep it running you have to hold the acc down to the floor and it just spits and backfires out the intake will not rev up over 750 rpms. as soon as you let off the gas it will smooth out and idle fine for a second and then die if not pump the acc and hold it down. i replaced pickup coil, plugs and wires. all help would be greatly appreciated with any ideas to fix it. also it i can start to drive it and after a few minutes it will pick up and drive better but i am afraid to stop anywhere between point a to b for fear it will start again.