88mustang347

I have a 1988 mustang with 347 and the starter would not start when it got hot. But would jump start?this went on for a while, thenone day I tried to jump start and it was trying to start and it would notstophad to disconnect the battery. I bought a new mini starter, put it on "what a pain" turn the key and nothing...took starter back and got old style and still nothing! replaced ground wire and turned key and the starter was just spining. disconnected the battery! replaced the soliod and the starter will not engage? I pushed jump it and it started. It will start every blue moon? after 50 trys? Please help! thanks, Jason