You have connected the wires to the wrong plugs.
check cap and rotor..... check valve clearance "cold"
nevermind it ended up being the ignition coil
I would replace the spark plugs after 50K, the wires and plugs again at 100K.
you either did not gap the plugs to spec or you put this wires on wrong
one of your wires is most likely loose so check that and if that isn't it make sure your spark plugs are tight
you have 2of the plug wires on the wrong plugs or distributor cap
You may have switched the ignition wires when you changed your plugs. I did this once and my kia started, idled terribly, then stalled after trying to drive. Go back and swap the wires that fit on top of your plugs and see what happens.
There are ( 3 ) spark plugs screwed into each of the two cylinder heads on the engine , for a total of ( 6 sparkplugs ) firewall 3 - 6 2 - 5 1 - 4 front of Ford Aerostar There are spark plug wires running to each sparkplug
spark plugs are either not put in right or gaps not right.Also check your spark plug wires.
a vacume hose must have came off the engine
If someone who knows what they're doing changed them, it's hard to guess. If someone incompetent changed them, they may have hooked the wires up in the wrong order.
I'm not a mechanic but it sounds like there has been a mixup involving your spark plug wires , either at the coil pack or at the spark plugs