2001 Chevy Venture starting

I have a similar issue with my 2001 Chevy Venture, last year we had a friend look at it and he found the "fuse wire" running form the battery to the fuse box inside (below the dashboard) on the passenger side, was corroded. We had a new battery installed about 2 months ago, my brother in law found that the positive cable of the battery was not tightened properly (which he tightened), now we have another issue: We went to go start the van, and heard one click and that was it. Waited about an hour and the van started right away, the next day started like a champ, the next day turned the ignition the rear air compressor went on and heard one click, waited for the compressor to go off and it started. Today same thing. Turned the ignition, compressor on / off, after about 5 minutes it started. Any thoughts? I'll gladly replace the starter if it saves me the hassle of guessing from day to day if the van will start.