van has trouble starting

When was it last tuned up? When was last oil change. When was air and/or fuel filter changed? Too many missing pieces to this query to give you any useful hints.

First try checking the battery. Not only if it charges properly but if any loose cable. Cracking mostly means that the car needs more power or recharging, while complete silence is a very bad sign.

If not the battery, check the last time you replaced spark plugs and other regular maintenance doings. It can be also a clogged gasoline filter (I doubt it but who knows. I'm guessing in many things that can cause your problem by using the year and brand vehicle). Do not replace unnecessary parts, you might waste lots of money for nothing.

The car is very well maintained in terms of oil, air, and such.

Well it doesn't seem likely to be the battery since it cranks fine. no problem there. it just cranks for awhile w/o actually "catching" and starting properly. the sparkplug wires are new....of course, that doesn't necessarily mean the spark plugs are new. Maybe I'll suggest that to my mechanic.

Apparently that is not the case or you wouldn't be having this sort of starting problem. Has the mechanic done a proper tune-up or not? That also would include changing the spark plugs. Spark plugs replacement are part of thorough tune-up.

Amongst a few others are further problems such as weak fuel pump and/or fuel filter and/or restricted fuel feed...pollution control valve, mass air flow censor, etc.

There could also be a further issue with electrical as well. The car seems to need a thorough mechanical and electrical diagnosis.

I'm not sure if ignition circuits are the same as in the '70's or not, but there used to be two ignition leads from the switch. One had a resistor when the switch was in the 'Run' position, and the other provided straight battery voltage for a hot spark while starting. If that's still the design, it's possible there is an intermittent fault in the 'Start' ignition lead.

Experience indicates that most such problems occur in the resistor of the 'Run' circuit, but it is at least possible the opposite situation is occurring here. I kind of doubt it, but it might be worth checking into.

What I understood and experienced with a vehicle from the 90's is that when the ignition switch is falling, there is no a single sign that you can start the vehicle. In my vehicle it was a freaky situation when it didn't start and didn't made a single sign of life when I turned the ignition.

By luck before buying a new starter and after testing the relays, I decided to change the ignition switch, and this vehicle still running fine up to today.

The vehicle didn't crank at all when the ignition switch was the failure.