I just put a remanufactured 351W in my 1986 F250, now when i start it, first it idles high then slowly dies. It doesn't start very easy. It has a four barrel, but only the primaries are hooked up. Timing is uncertain, their is no indicator on the timing cover, but it is pretty close. The distibutor is half way between stalling one way or the other. please help

 

Since you mentioned the timing: You probably have an EEC distributor. You can't adjust the timing on these, the EEC computer controls the timing advance. The one thing you can adjust is the distributor alignment. But you will need to be certain that the engine is at TDC when you align the distributor. There should be a little pointer over the top of the harmonic balancer that you can align the timing marks with. Then you have to align the notch in the distributor shaft with the notch in the adaptor. [link:www.ford-trucks.com/dcforum/DCForumID103/1121.html| Check this thread here] for photos and description of how to align the distributor.

That's probably not the main problem, but at least you will have eliminated one possibility and it's easy to do. Make sure that all the wiring is properly connected to the O2 sensor, coolant temp sensor and throttle position sensor. Also make sure the wiring and vacuum tubing is properly routed to the the EGR solenoids and the MAP sensor.

You said it slowly dies after a fast idle. You might also check for fuel starvation. Disconnect your fuel line from the carb and put the end of it in a jar. Then crank it over a little to see how much fuel the pump is putting out.