Truck: 1989 F150 Ex Cab 351- V8 - 5.8 Liter EFI - dual tanks - 2WD
190,000 miles.

Problem:  The truck starts and idles fine - most of the time.
(Yesterday it was a bit muggy and it took a little time to get it to
turn over initially.  I'm working outside and it's usually dry when I
tinker with it.)

The main problem is that I can drive it around for 5-10 minutes then it
will start to hesitate a few times then totally die.  It doesn't buck
or jump at all when it hesitates, the engine just stops running.  The
first few times this happened I wore out the battery trying to restart
it and had to be towed home - not fun.

The last time it happened I pulled over at the first sign of
hesitation, put it in neutral and gave it some gas.  The engine started
to run again, then died - just like the other times.  I sat for a few
minutes, then it started right up again.   I was able to get home on my
own power this time - but I made sure to stay within a mile of my house
so that drive was 2-3 minutes.

This happens every time I drive the truck.

I replaced the Distributor Mounted TFI and Ignition coil 2 weeks before
this past episode.

The truck used to have really bad stalling problems at idle, but I got
rid of those (THANKS TO THIS GROUP!)  by replacing the EGR Valve and
sensor, IAC Bypass, PCV valve, Crankcase Breather Filter, and Spark
Plugs made all these changes in August - October of last year.  The
truck sat all winter and has maybe 20 miles on it since then.  Before I
made all of these changes, the truck used to hesitate on the freeway,
but I haven't had the guts to go freeway driving in this thing since
early August.

I'm also still getting a code 33 on my reader.  The EGR and EVP are
both new and the volts / ohms are in the correct ranges for both parts.

I checked and cleaned the new PCV valve and hose to the engine.  The
valve smelled of gasoline (problem?) and the hose was nearly clogged.
I cleaned the valve and hose.

Other points / questions to help with diagnosis:

The truck also has a knock/ping on hard acceleration.

Vacuum pressure:  If I unplug a vacuum line after turning the truck off
and there is a hissing sound - like pressure equalizing with ambient -
does that mean the vacuum system is OK?

O2 Sensor: Would a bad O2 Sensor cause the main hesitation/quit problem
without causing other problems?

Fuel Filter:  For the life of me I can't find the in-line fuel filter
that my manuals (haynes/chilton) say is on this truck.  I bought a new
filter last year for this engine/truck set-up but have no Idea where to
put it.  The lines go from the tanks to the selector switch/reservoir
to the pump and into the rails.

When the truck gets up and going, I'm only looking to use it for
camping and random other trips, maybe 1K - 2K miles per year.  Not
anything close to a daily driver.

Thanks in advance for your help, this group has been awesome to me!