You might check fuel pressure and fuel filter on hard starting and
timing it to be set at TDC with timing jumber plug disconnected to be
set stock, myself I run my 89 at 8 BTDC and use higher octane fuel and
it runs great and gets good MPG too.
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TheSnoMan.com

I have an '89 Suburban 4X4... had hard starting like you described. It
turned out to be the contacts on the fuel pump relay (mounted on the
firewall).  The relay normally pulls in when cranking and applies
power to the fuel pump untill either the engine oil pressure switch
closes or the power steering pressure switch closes (I forgot which
one) to provide power to the pump.  If you like let know and I will
look at the wiring diagram in the GM shop manual. If these relay
contacts don't make up to power the pump, then you have to crank
untill you build up oil pressure and the pressure switch closes.  It
might be a lot of cranking if it's hot (thin oil) which is what mine
did or if you have very low oil pressure at low RPM (if it's engine
oil pressure which I think it is).  Mine was worse when the engine was
warm vs. when it was cold. (oil viscosity being the differance).