I have a 4.0 l mpefi engine in my 96 XG panel van. It will not start in the mornings. Cranks fine, and the fuel pump runs. It seems to catch every now and then but won't run. It has spark, though weak. If I try to start it later in the afternoon, it will fire straight up. I can clutch start it ok, but when it does it smells as if it is flooded. Once running the engine is fine with no signs of problems although the milage has dropped off some. I replaced the head approx. 10,000 kms ago and the engine is mechanically fine. Compression is good across the 6 cylinders.

My car does the same its got stuffed injectors, altho mine will start if I keep winding it

One of the injectors may be blocked, stuck slightly open (ending in slight flooding) or just stuffed. Also weak spark could mean dying coil, stuffed distributor cap (assuming it's running distributor) or stuffed leads.

Change the coil over and see if that fixes the problem.