Unfortunately, I'm still versing myself with these cars.

My dad had a couple (literally a couple, two) Camaro's when I was growing up. He had an older third generation RS, which I remember very vivdly.
Beige cloth interior, pure white with twin red stripes down the center, top of the front bumper to the trunk. T-tops as well, which I also remember quite well for leaking a lot in Panama City, lol. Many a drive holding a trash bag on the roof while we made the trip quickly home to the garage, lol.
The other one was an anniversary edition LS1 (1998, same year as mine I think) that was gold-flake paint, with red velvet leather and suede interior. Automatic, w/ T-tops.

I don't know much, but basing the fact that you have an SES light going off, and poor fuel economy, sounds like maybe a firing problem? Sounds basic, but have you checked your spark plugs recently? If you've got a fouled up one that's not sparking, that can lead to other problems.
I would honestly recommend picking up a code reader as well, though I don't know if your year is OBD 2, or OBD 1. I got some el-cheapo ones that just read the codes out to you, and you match it to a book. They cost me $15 each, + $3 for shipping. Work well, if not very basic. You can't clear codes with them or get any other real information out of it, but it gives you the fault codes that have popped up, or ones that are still active.

 

I put in NGK plugs and a $70 set of wires (forget the brand) less than a year ago, and have driven less than 10k miles since. I also changed one of the ignition coils that was dying. I plan on buying a bluetooth code reader that can work with my phone when I have the money.

 

test fuel pressure, low or high fuel pressure can cause what your seeing. pull 02 sensors and check for fouling. 02 sensors do get old and lose effectiveness. if they have never been changed now may be a good time. test you engine temp sensor, if its failing and showing a very cold false reading it will cause what your seeing. check catalytic converter, if its plugging up it will cause what your seeing.

 

Sorry for bumping this, I've been busy and haven't checked the post. I haven't replaced the o2 sensors because I haven't got a bad o2 code, but if they could still be bad I'll look into replacing them. I haven't had any issues with temperature readings. I don't know how to check the cat.

 

back pressure test starts at 353

 

I'll have to have that done by a local shop or something. Nothing I can do about it at home.

 

I am not saying it is the issue but my 3800 had random misfire and MAF sensor codes. It turned out to be the connector going to the MAF. I would pull the #3 plug if you got that code just to take a look.

 

Well, I believe my old MAF was bad. I was getting rough idles and occasional bucking while driving. New MAF fixed that. The code just isn't gone.

 

if you dont clear the codes they will stay for a time. it takes a few runs without issues for the code to clear itself.