My car makes a rattling noise when I accelerate on 1997 Toyota Corolla

I know it's an older car (1997 Toyota Corolla)....but it's been well taken care of by only 1 owner before me....when I hit the gas it rattles and then it eventually goes away when I let my foot off the pedal...but then every time I hit the pedal it makes the noise. I put midgrade unleaded fuel, could that be the reason?
I already use the mid grade gas, not the lowest but the second up....89 or something like that, can I do anything else...I think it comes from the left part of the engine...I never really opened the hood for this particular problem...so someone said it could be "Spark Knock" how can I know for sure what to fix...the EGR/Sensor/ignition timing/cylinders...i don't even know where to start! Please help, I don't trust anyone, they'll charge me an arm and a leg, and plus I'm a woman!!!

5 answers 2 comments
I have a 97 corolla too and I have the same problem and I can smell the exhaust. At first I thought it was the flex pipe but now I am not sure. Can somebody help me
mostlikley your catylatic converter
If the engine was suffering from spark knock or a misfire due to gas quality/octane rating it would illuminate the check engine light (yellow icon on dash). Could the noise you hear be an exhaust heat shield that is cracked or damaged, or a cracked exhaust flexible/accordion pipe directly under ythe engine. Have seen a few cracked exhaust manifolds as well. If the yellow Check Engine light is not on the problem is not as serious but should be checked out.
Would what you're saying affect an emissions test, cause it passed
i have a toyota corroll 03 THAT I LET SIT FOR A YEAR DUE TO DEPLOYMENT NOW MY CAR RATTLES REALLY LOUD ALL THE TIME I TOOK IT THE TOYOTA DEALERSHIP AND HAD IT LOOKED AT, THEY SAID THE TIMING CHAIN AND VALUES HAD TO BE REPLACED SO I HAD THAT DONE,NOW AFTER GETTING REPAIRED MY CAR RATTLES EVEN WORSE AND IDLES ON ITS OWN. WHAT IS WRONG WITH MY VEHICLE
I have a '98 Chevy K1500, and my truck has the same exact problem. I think it has to do with the timing, and here is why. You are not supposed to try to adjust the timing on this truck, but a mechanic once did on accident, and the rattling was really bad. He did his best to 'reset' the timing, and now the noise is not as bad, but it is still there. I think the timing is still off, and I will probably end up taking it to the dealer to adjust.
Guys I had the same issue with my Nissan Altima 2011. Started hearing a ticking noise that goes up as you pedal and stops when you let you foot off the pedal. And sometimes I used to smell exhaust gases in the passenger compartment.

Took to the dealership and they charged me $150 to diagnose. The problem was the manifold gasket was cracked.

The repair took about $850 to repair including labor and parts.

I would suggest you go else where to get it done cheaper. The gas in the passenger comparments could have CO which could be dangerous.

More info:
http://repairpal.com/exhaust-manifold