[MagicRat]

Hard starting.......do you mean it turns over slowly??
If so, chevy starter motors sometimes get heated up by the exhaust too much and their electrical resistance goes up, making them turn over more slowly. Often, there is a heat shield that goes around the starter. If yours is missing, they are available aftermarket.

Also those thumps might be a loose exhaust, bad transmission mount or loose transmission crossmember.