The 2.4 quad 4 twin cam is a far better choice in a used Grand Am. It's more reliable, VERY maintenance free (no timing belt like most 4's) requires virtually zero maintenance before 100,000 miles and is extremely strong and responsive.
My 8 year old quad 4 has run perfectly since new, and never required a single repair or even changing of the spark plugs.
I've added a cold-air induction system, and mine easily leaves most Civics, Corollas, Focuses, ALL pre-2007 Camrys and most other 4 (and many V-6) cars in the dust.
My mind is definitely made up to purchase a local 97 Grand Am GT with the 3100 V6. I had an Alero of 2001 ilk, and she treated me very well though 70k miles of horribly rough pizza delivery driving (probably about 250k worth when you consider it's all stop/go and in-town driving!) This car is $1500 and looks in great shape aside from a few cosmetic scuffs and some minor paint fade in a few places. The first test drive went well, but was entirely too short due to not having dealer plates and not wanting to get any tickets we didn't go very far at all. Going back for a REAL test drive tomorrow - I can't wait!!!
Good luck with your GT, hope it's still out there rolling and kicking!
I've had a 97 GT for about a year and a half. All I've done to it is a power steering pump, because the old pulley stripped off the gear on the shaft, and it's got about 180k on it. I've put about 18k on it myself, and now I don't want to get a newer car, because I like this one so much. I even hit a deer, and all it did was crumple the hood up a little. A new hood and that's fixed.
I'd recommend this car to anyone who's in a money pinch. They're long lasting cars, and cheap at that.
I gotta side with the 3.1 over the 2.4 because of reliability issues. My first car was a 1996 Grand Am GT with the 3.1 in it. Great powerband on it. Unfortunately I wasn't very mechanically inclined, and when I overheated the engine, I cracked the heads. I've learned since then.
My next car was a Cavalier Z24 with the 2.4 in it. Again, another fun car to drive. However, the engine's timing chain jumped without warning and destroyed my engine. The 3.1 was fixable at a cheaper price. The 2.4 would have had to be replaced entirely. So, 3.1 is definitely the way to go.