Get it scanned. A proper scanner would show what is wrong. A few probable causes, namely speed sensors, AT position switch, wire harness and eventually TCM.
It is usually integrated into the distributor. You need to to the complete unit( distributor).Set the TDC mark correctly and just pull out the old and install the new.
Ball type clip holder. You need to press the mirror to the fixture by making sure the one on the mirror meets the clipholder on the side mirror casing.