93 Ranger fuel problems

I have a 93 Ranger that is having some sort of fuel problem. If I run
multiple errands, it gets hard to start. It turns over, but will not catch.
It will also sometime just cut out running on city street, the interstate,
stopped at a light, etc. The only consistant thing is that it starts great
the first time of the day, but gets worse the more you start it in a short
time.

I replaced the fuel pump 7 months ago, and that seemed to fix it for about 3
month, when the symptoms started again. After about a month of getting
worse, I made the time to take out the new fuel pump and return it to NAPA
(they exchanged it with good graces after I showed receipt and old filter.)
I also replaced the fuel filter when I replaced the fuel pump the first
time. Now after 2 months with the new pump, I am having the same problems.
Any ideas? Did I get 2 faulty fuel pumps? Is there some other electric
switch that gets flaky as it gets warm?

Thanks for any ideas.

Steve

I might look at cleaning the injectors and the MAF sensor next.

Possibly it's not a fuel problem- ignition, maybe?