i just bought a 2000 v8.the alternator is new. the battery new.sometimes when i try to start it it cranks and cranks and nothing.while its trying to start it backfires and sounds like its misfiring. then when it does start it runs fine and when i shut it off it starts right back up i shut it off and restart it 20+ times. then the next day wont start same thing.could this be the starter? or something else

 

You say it cranks an cranks but does not fire? if that is so then no its probably not the starter because it is turning the engine over. need to fall back to the basics when it does not fire, does it have spark? is it getting fuel? (or enough fuel, low fuel pressure)

 

i think it sounds like low fuel pressure, and probably a bad anti-drainback valve in the fuel line. try turning the key to on and waiting for the pump to shut off before engaging the starter, see if that helps if not have the fuel pressure checked.

also which v8 do you have (they offered 3 in 2000) if you have the 5.2 or 5.9 check plug wires are tight and distributor and cap are clean and coil is firing consistently

 

Change your spark plugs with Champion Copper spark plugs gap at .040