hard start 91 s10

I have a hard starting 91 S10 2.5 2wd. I have to crank it for a minute or 2 to get it to start after that it runs fine. I have replaced the fuel pump and the relay. I have checked the coil and replaced the plugs and wires. Also it doesnt have a hard start all the time and there is no real pattern as to when it happens. Im at a loss and dont want to continue to throw parts at it. If anyone has had a similar issue Im open to suggestions

Have you checked the timing? Its possible that the timing could have a bit of a retard.

 I thought the timing was electronically controlled

The problem turned out to be a bad Ignition Control Module