I have a really bad knock and when I sit at a light or at a stop (and the car has reached opperating temp) The idle will almost die then catch itself and rev to abuot 1000 and then die down to like 250 and sputter and then catch. I thought it might be bad gas but I have refilled three times and I still have the knock. The knock is over a 3000 rpm band to. I have no vacuum leaks, Timing is at 0*. My mods are in my sig. Something tells me my timing is off. I just had an internal vacuum leak fixed and I am thinking they didn't set the timming right. What could be the problem. Could me TPS voltage be off?

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1990 RS 305 TBI T-5
.5" turbocity spacer
Edelbrock TBI intake
180* stat
Summit 14X3 OpenElement W/k&N
Hooker 3" Areochamber
MSD - Wires, Cap, Rotor, Coil
Bosch Platinum +4 plugs
Metallic Red w/28,000 Pampered miles
(Still have the original wiper blades)

 

Check your pick up coil in the distributor if you have he EST Distibutor, also dont use anything else but AC Delco plugs, anybody ive known thats has a Thirdgen bird or camaro, if they didnt use AC plugs the car ran like crap later, AC Delco rapidfire's are better plugs, and work excellent in any Small Block chevy,

 

Sounds like base timing. Recheck it and you shouldn't be hearing knock because the ECM will retard timing before you can even hear any detonation! So maybe it isn't timing.