I have a 97 E350 Club Wagon SD w/ v10. It has 215k miles.
The past few days the engine cuts off, sometimes just for a second, then back on, other times it was worse. I pulled off the road one time and it would start, run from 1-30 secnds and cut off. Kept doing this for a while, then would not start at all for some time.

I noticed that the Temperature gauge was going all over, jumping from the normal reading to above Hot, down to Cold (less then a second). When the engine cut off, the temperature gauge had just jumped.
I thought maybe the computer reads the sensor and if out of range shuts off the engine. Couldn't find a loose connection, so i replaced the temperature sender, that wasn't it. Not sure if the temperature reading is flopping as a cause, or a symptom of the problem?

Sometimes, when it refused to start, i could hear a relay in the engine power distribution box fluttering (the engine check light would strobe at the same time, about 10 cycles a second).
I wiggled wires and connections and couldn't find any thing. Swamped around relays, not a relay problem.

ADDED : The relay that is fluttering is the Fuel Pump relay.

Any one got any idea where to start looking?
After tinkering with it for an hour yesterday, all of a sudden it started up and ran fine. I couldn't get it to cut off wiggling wires. It was fine for hours of driving, then starting cutting off and on again.

Got it home, but can't figure out what to look for?

 

Check for broken ground wires, loose or corroded connections to grounding wires; bad battery cables, and blown fuses.

I suppose there's no check engine light yet?

 

Sounds like the power to the PCM is getting cut off. That would explain the check-engine light and fuel pump relay flickering at the same time.

Like Big Orn said, check for all sorts of loose connections.

 

So far I can't find loose wires or connections, but, I took out the fuel pump relay and i could still hear a clicking noise in the engine. Actually, rather then 10 cycles a second everything was clicking around 3-5 times a second.

This is a van, so i took off the inside engine cover and found the clicking was a solenoid, I think on the EGR valve? (Hey, i don't know a whole heck of a lot about engines). I didn't take the time to find out exactly what it is, but, I disconnected it, and i could hear another more faint clicking. All at the same rate. I had to take socket extensions put up to my ear and tried to find where the more faint clicks were. Actually my son found it was from the Transmission (this is sounding more bizarre isn't it?). I unplugged the connector that goes down to the trans and all clicking finally stopped. It seems that every output from the PCM was strobing, at a very steady rate, not like a loose ground. I was sure the PCM was bad. Still don't know for sure.

But, i called a mechanic I go to and he kept telling me it was most likely the fuel pump. But, i had the fuel relay out, i just didn't believe him. Well, he told me to go get a can of starter spray and see if the engine starts with it. If it does, it is the fuel pump. Hmmm. Okay, I sprayed it and it didn't fully start, but it did fire a few times, which it hadn't done before. More than that, the strobing totally stopped.

We tried to start it a few more times and it just made a few pops, then the battery died (was tinkering with this all day). At the store i also picked up a can of Techron fuel cleaner. The strongest one and put it in the tank. 2 hrs later when the battery was charged the thing started right up like nothing wrong.

Now, do i have a bad fuel pump? Electrically bad, or maybe dirt got stirred up?

I have to take it in to change the pump, it's in the tank. I'm not doing that.

At this point i am not confident it is the pump, or loose wire, or what.
But, has anyone heard of the PCM strobing the relays, the engine check light, the solenoids, everything strobing if the fuel pump doesn't work? Sounds odd to me.

 

For those who would like to know, it was a lose ground wire on the PCM.
(Ford dealer charged me $210 - took their tech 2 hours to find it, 1/2 hour to fix it.)
At least it is back up and running smoothly and reliably again.