2000 Jeep Laredo won`t start

How did the starter check good? The only way to check the starter is on the vehicle with a amp meter. Testing a starter off the vehicle is impossible so if thats how it was done then I would replace the starter motor. Thats what is usually causing the drag of a slow crank, also make sure the battery connections are good, if I have a doubt I will cut off the ends and replace them to be sure, it only costs a few dollars because sometimes right where the battery cable meets the post is where there will be real high resistance. Hope this helps