P0300 DODGE -

Question

i had a problem with the truck shuttering at the speed of 3000 rpms if i were to push it over that mark the engine would bog down badly. so istarted with replacing the spark plugs broke a few of the bolts and got them replaced and now its like new. but when i went to start it and run it. it ran like total shit it has a hard time getting into 3rd gear still cant go above 3000 rpms not sure what to do from here.