I think the spark plug wires are crossed on a 1989 pontiac grand prix 2.8

No, a plugged converter would cause the engine not to breathe properly. Too much back pressure would stall the engine or make it run very poorly. It would not be local to any one cylinder-all of them would be affected.

To diagnose a misfire in one cylinder, well, you start at that cylinder. It could be ignition related- the spark plug and spark plug wire for #6, possibly the ignition coil for #6 in the coil pack for the engine. (A v-6 would have 3 coils in the coil pack, one coil for 2 cylinders.) It could also be fuel related, so the fuel injector for cylinder 6 should be considered. And the last reason for a misfire is usually the most expensive repair: low compression in #6. This may be a head gasket problem, or a piston ring problem, or one of the valves for #6 may not be sealing well, causing low compression and the resultant misfire. The engine computer codes a misfire when it senses low power output from that particular cylinder. The misfire causes a lag in crankshaft rotation, and the crankshaft position sensor senses it.

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the coilpacks are labeled 1-6 designating which cylinder the wire goes too,i am 90% sure that the side closest to the radiator is 1-3-5 and the "firewall" side is 2-4-6, i usually take 1 at a time loose ;)

I would recommend that you replace the plug wires at the same time because the boots usually break when you remove them and with the engine rotated forward they are easier to get at.
When re-installing the new plugs, it is important to make sure you get several turns on the plug before putting a wrench on it. The last thing you want to do is cross thread a spark plug. The new plugs should almost bottom out before requiring a wrench.

are spark plug wires on a1996 pontiac grand prix the same sizes?

1994 Pontiac Grand Prix 3.4 liter DOHC V-6 VIN "X"




1994 Pontiac Grand Prix 3.1 liter V-6 VIN "M"



Hope this helped; TY for using Fixya (remember rated and comment this).

My sincere apologies for the delayed response.
I am personally going back to answer your unanswered question.

For the 2.8L
Firing Order:
1-2-3-4-5-6

Cylinders:
......(back)
1.......3.......5
2.......4.......6
......(front)

Ignition Connections (Spark Coils):
........(back)
.|.1..4.|.|.6..3.|.|.2..5.|
........(front)

Again my apologies....
Let me know if this helped...

check the alternator charge level .
check the battery + and - are not lossing
if nothing then you have wiring short

u have 2 engines that may be in car, see links for both set ups.
3.4L
http://autorepair.about.com/library/firing_orders/bl-fo-8203.htm
3.1L
http://autorepair.about.com/library/firing_orders/bl-fo-8202.htm

You will need to remove the coil packs first. To remove coil packs, undo 4 bolts and tip the coils over to the side.

Users on the internet say also that you can remove two engine top mounts to access the plug wires. See links below:

WikiAnswers - How to change spark plugs on 1999 pontiac grand prix

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