Loss of power after coil pack replace

I have a 95 Aurora with 99,000 miles on it. Last week it started idling really rough. I took a look under the hood and found that one of the terminals on one of the coil packs was all rusted and wasn't firing anymore. I replaced the coil pack with one from Autozone (manufactured by Wells). Everything was fine for about a week and now the car feels like it's running only on a few cylinders and has no power at all. I checked the spark on the coil packs and found that one wasn't providing spark consistently so I replaced it and the other two coil packs but it made no difference. There are no SES lights, the car fires right up and idles smooth. However, when I step on the gas there's no power. Exhaust is nasty smelling (compared to when it was running normal) I've seen the posts about the FPR but don't think that that's the problem since I'm not getting spark consistently across all the wires. Is there something upstream of the coil packs that might be malfunctioning? Any ideas?

How are you testing for spark?

I checked the spark by hooking up a timing light and moved the pick-up from wire to wire.

Have you checked your plugs and plug wires. You may have a bad plug. If it's never been tuned up in 99K miles then you should change them. Don't go with aftermarket, go with GM recommended replacement plugs and wires. I've read threads from another forum that the aftermarket wires won't work as well and typically fail within 6 months.

These cars operate on platinum Delco plugs, what I would suspect is when someone goes aftermarket they grab a plug that is not platinum tipped and ends up being a colossal waste of money.

So yes I agree 100% stock plugs/wires

Thanks for the info guys. Olds dealer just called me up and said the same thing (should replace plugs and wires) but they said real problem is ignition module which costs $500 + $150 labor.

Anyone have recommendation on where I can get a good set of spark wires at a reasonable cost? I looked on one website for OEM parts and it had them for $150.

I paid around $85 at my local Buick dealer. Call around. Otherwise GMPartsDirect, RockAuto, VanChevrolet, et. al, are good web sites to surf for these parts (you can get the part number from GMPartsDirect usually).

Thanks for the info on the websites. I check a couple of them out and they have just what I need.