Starter problems

I recently replaced a starter in a 1992 Jeep Cherokee Sport 4wd, 4.0 liter, 6 cylinder. I have been having problems with the Jeep starting. I thought this would solve the problem. It didn't. Although the old starter was bad, I am still having problems in starting the Jeep. Sometimes it will start, sometimes it won't. If I giggle the battery cables, sometimes it will start. Could it be the ground wire? I need help. Thanks.