random and spoadic misfireing

[slreno1217]

i just bought a 1999 venture with 108,000 miles. when i bought it the battery was dead and wouldnt start. the dealer i bought it from jumped it and i drove it and the check engine light was on and was misfiring like crazy. that seemed to go away the longer i drove it. well i bought it because it didnt seem like anything major. well they had to replace the battery because it wouldnt stay charged.

the misfiring is very random and sporadic. i can make it get a check engine light by pressing the gas to the floor it wants to bog down passed the halfway point of the accelerator. but before that point it runs great! but if i floor it it will bog down and start misfiring at an idle and for a hour or so then it will go away and run great. and the check engine soon light will eventually go out.
any ideas on what might cause this?
i sorta want to rule out plugs and wires
because it seems it would do this all the time if it where plugs and wires?

oh yea when the light comes on it is a misfire on cyl. #3

oh and one more thing. this vanture has a brand new intake gasket on it. i can see it and it is new.

[meggabad]

How do you now its a misfire on cyl 3? You read the codes and thats what it says? Is so, check the wire for that cylider, could be you just have a wire grounding out. Also could be one of the three coil packs. Since it just had the IMG replaced, maybe the mechanic smokes dope and didnt put the wires back in their respective order, or cut the jacket on the line that goes to cyl 3. Also, make sure that the wires are completely plugged onto the plugs nice a snug. I've had vehicles brought to me with that very problem,as simple as it may sound.

I realize the wires on these vans are not the easiest to get to, but if your looking at all three coils mounted to the rear cylinder head, the order of wires from left to right are 5-3-2-6-4-1

Cylinder locations are as follows:

1 -- 3 -- 5
<-- Front of motor <--
2 -- 4 -- 6

Since the cylinder you have a problem with is on the backside and hard to see any obvious problems, I would start by making sure that the wire isnt damaged, or burnt in the exhaust manifold grounding out. Then check the plug itself, then wire/plug connection. Could be a coil, but I would check these things firstand go from there. Good Luck! -Drew