2000 starting and running issues

I have a 2000 Safari AWD with the 4.3 with 122000 mile on it. About a week ago I drove it to work and it ran really rough. I got to work and later put a Scaner on it and it came up with multi cyl miss fire. On the way home it ran fine. I parked it and about an hour later I went to start it and it wouldn't start. I could hear the pump run so I checked spark and had none. Tune up was done less than a year ago. The van sat parked in the driveway for the week and I just for grins and giggles tried to start it when I got home and it fired right up like nothing ever happened. Where do I start so I dont get stranded somewhere with it? Thanks for any help

P0300 is almost always caused by faulty secondary ignition parts. The 4.3L can be quite fussy when it comes to the brand of parts that are used. Certain brands of parts can cause problems even when they're brand new. They can cause any of the P0300 series DTC's to show up along with poor performance, and a no-start condition. They run the best when using AC Delco 41-993 spark plugs, AC Delco or Autolite professional series plug wires, and AC Delco distributor cap and rotor.

Other common problems are:

Clogged vent in distributor housing causes excess condensation inside the cap... remove the vent.
Low fuel pressure and/or excessive leakdown... check them first.
Ignition coil shorting to ground... check & replace if necessary.

These are the basics to check... post your results.

It ended up being the coil. Runs better now than it has in a long time. Thanks

Glad you found it! Thanks for posting back with the fix!