5 litre engine trouble

[Big-D-94GT]

just a few days ago i was driving around in my 1994 gt and i was only going about 35 km/h around my house and i heard this weird noise like a ping from the back passenger side of my engine. i stopped and checked it out and it sounded like when a hot exhaust cools down like a pinging noise and a bit of a hiss. now it idles irradictly at times, and sometimes smells like its running rich and lacks power. and when i start out in first gear it sometimes lopes and lurches, im not sure what the problem is i cant see anything and im not sure where to start. i dont want to take my car to amechanic unless i absolutely have to, any help would be awesome

 

[CC'S95GT]

did you look for and exhaust leak.

 

[Big-D-94GT]

i put a new exhaust gasket on recently beacause it was leaking. would a small leak really cause this big of a problem? and when it idles it revs high then really low then high again etc. it only doe that sometimes. could timing be an issue that would cause all of this?

 

[RockstarMentality]

the revving up and down at idle is most likely a vacuum leak.

 

[CC'S95GT]

is sounds like you have a couple problems.
Pull codes and see if you have any stored. The cel doesn't need to be on for a code to be present.
Finding the exhaust leak should be easy enough and shouldn't cause the idle issues.
what mods do you have?
when was the last time the car had a tune up?

 

[98green5.4]

It sounds like vacuum leak, but like desertcox said, it also sounds like it could be a few things maybe.

did your exhaust get louder when you noticed that noise while you were driving it. and does it sound louder now?

 

[BLOWN 95GT]

Did you check the back of the cylinder heads where the smog, or egr crap goes into the heads? That will sound just like an exhaust leak from the collectors and you will loose power.