What am I missing?

my 1998 windstar 3.0 runs fine for a certain length of time (say 30 mins) then it suddenly dies and wont restart till it has been left for a while. Its not over-heating (temp gauge stays right in the middle) and has had the coil pack, fuel filter and fuel pump changed within the last 2 months. What am I missing?

No codes?

Things to check: Fuel, air, spark, compression!

Make sure there is fuel pressure on the fuel rail. It could be that the fuel pump stops pumping after 30 minutes. Make sure the injectors are working. I had a problem on a vehicle where all injectors were wired such that if one shorted, it prevented all injectors from working. It only happened when the injector was hot. It happened to me more than once, so this failure isn't a one off thing.

Air: I doubt that anything in the air cleaner is responsible.

Make sure you have spark. Pull one or two wires and check for spark while turning it over.

Compression.. well it can be difficult to check compression on a hot engine in a van. Maybe it's good enough to listen to the cranking, and go by how labored the starter motor seems to be.

The computer can real foul things up if it gets a bad reading from a sensor. For example, a bad coolant temperature sensor will cause the computer to compensate by adjusting the amount of fuel. I had a case were a car would only idle b/c the coolant temperature sensor was telling the computer that the engine was operating in 450 degF! At idle the computer ignored the sensor, but the moment you touched the throttle the computer would cut off all fuel to the engine. It was intermittent, and worked fine if the computer was very cold (<10 degF) or very warm (>60 degF), but it didn't work when it was in between.

If you can get access to a scan tool that provides live data, you can see if there are any sensors giving crazy readings.

Ok update - its dead dead. Sitting in my garage just now. Pushed it back in there since it thankfully died in the driveway.

At this time I have been unable to get a code reader - if this continues I am going to go and 'hire one' from oreily's. Im unemployed at present so money is a bit tight.

Other than that - pulled a lead off and did the old screw driver test with it to see if there was a spark.... and NOTHING. Seriously - there is nothing. How do I test the coil pack?

ok another update.

So wider info - I recently topped up the tranny fluid with the Lucas additive (tranny is on its way out at 200k miles). As I was putting the fluid in, my hands were compressing a number of pipes and cables to make space for the bottle. It was shortly after I was doing this that it died. The engine had been running for about 30 mins - which I am beginning to suspect is coincidence in this case.

Looking at the engine - the wire harness for the crank sensor is right infront of the tranny dip stick. The wires themselves are not in looking the most healthy - kinked in places - although they are not bare at any point. Im beginning to wonder if I broke the circuit to the crank sensor. It makes no difference if I pull the wire harness off the sensor or not. The engine does the same. What are your thoughts? How would I test this?

Im assuming that Im talking about the right piece of hardware - http://www.autozone.com/repairguides/Ford-Windstar-1995-1998-Repair-Guide/ELECTRONIC-ENGINE-CONTROLS/Camshaft-Position-CMP-Sensor/_/P-0900c152800ae148

I have a '96 with the 3.8L engine, so my comments are based on that model. The sensor showed in the Autozone pages is located at the front of the engine, near the #1 cylinder injector, not back where the transmission fill tube is located. It senses the camshaft position. There is another sensor for the crankshaft position. which is located at the bottom of the engine, on the front cover, next to the harmonic balancer.

This page might help you diagnose the coil pack:
http://www.fordforumsonline.com/threads/howto-check-the-ignition-coil-pack-on-a-3-8-windstar.102/

If you have no spark then you need to resolve that first.