funny noise under load

[PIYIRIO]

hey guys, i lurk here quite a bit but now i'm having a problem i can't seem to figure out. to start off, i have a '92 base firebird with a v6 3.1 mpfi. for that past 4-5 months when i get on the gas i get a funny noise with the engine rev. its random, not a constant sound and once up to speed, keeps on worse when it drops into overdrive. i thought it may be the tranny but the shop said it's fine. i though it could be the exhaust because the way it sounds, plus i get some funky exhaust order out the pipe. not the smooth order it used to be. i did a tune up, (ie. plugs, wires, cap, rotor, coil) and noticed 2 sparkplugs were black with soot, alot worse than the others. i'm losing my job in a week so money is going to be tight on the repairs but it has to be done. right now i'm thinking it could be the injectors fouled or the distributor dropping spark. anyone know which of these are more likely? i'm just praying it's not a ring or valve at this point. god knows i can't afford a rebuild or another engine. sorry for the long read and thanks in advance for any help.

[Dan Vincent]

Have you tried your oxygen sensors? Do you have a check engine light on?

[PIYIRIO]

no check engine light and the o2 sensor was changed about 6 months ago. i checked the computer for a stored code, just in case, and nothing. at 4-5k rpm the noise goes away, and at idle it's not there either. only on acceleration up to 3.5k and cruise. between 3.5 and 4k it's really hit and miss random like, then smooths out at 4k. i guess it's just missing, but only sometimes, on those 2 cylinders.

are there any good places to pick up injectors at a reasonable price? i'm going to give that and the distributor a shot i guess. this place has reconditioned (urghhhhhhh >=\) bosch dri full set for $199: http://www.lindertech.com/reconinj.htm

[wantmorepower]

Are you sure that you are not getting some kind of misfire? Maybe arcing to the block?