Buick/Olds: 1992 Buick LeSabre 3.8 Liter - engine miss, buick lesabre, floor pan

Question
My friend, who lives a couple of hundred miles away has a problem with his Buick.

He says it misses on acceleration or on a "load" (going up a hill, etc.)
He says he changed the air filter yesterday.  The plugs were changed "about 2 years ago."  He says he doesn't know where the fuel filter is.
Do you think this is a fuel problem or an electrical problem or ?
Could you give us some help please?

Thanks in advance.

(I don't mind this question being "posted."  I don't know where I said for it not to be!)

Answer
It could be a fuel or ignition problem. Most likely since it only happens under a load, its ignition related. You didn't say how many miles were on the car or how many miles its been since the plugs were replaced. On the older 3.8, the plugs should be replaced every 30k miles or about every 2 years. If it has a lot of miles on it, which it probably does, the plug wires should also be replaced. I recomend them at least every 60k. It could also have one or more of the coil packs breaking down under a load, but you need some specialized tools to check them properly. Try the plugs and wires first.
Also if he wants to change the fuel filter, which should be done every 20k, it is either on the drivers side of the car, right in front of the rear wheel, or it can be on the passenger side of the car under the front floor pan. It is probably so rusted on by now that he wont be able to get it off without breaking the lines so be careful.