Well the car wasnt running so good, so yesterday I pulled the cap and rotor and they looked pretty bad, so I replaced them along with a new MSD coil. Put everything together and the car ran alot better, nice and smooth. Today as Im driving around, all the sudden the car nearly dies, So I let off the gas and drive very slowly back home. Now I have to be very easy on the gas, anytime I push the pedal down more than a little bit the car will studder and possibly backfire. Basically I drive under 2500 RPMS. There is also some blackening on the driver side butterfly valve of the TBI unit. Is this from the backfiring? I dont understand how it was running so good yesterday and now it runs like crap I have new wires that I could put on but how do I tell if the plugs are bad. Do you think this is ignition related or womething else? The car used to shake some at low speed cruising around 1700 RPMS, but it stopped once I replaced the cap coil and rotor, but now it is kind of shaky again.

 

First thing is check to see whether a lead has come loose.

Mark.

 

A lead to where? Well today I replaced 7 of the spark plugs, I couldnt get to the #8 cylinder plug today, But i did a test run and It ran good fo a while before it started to backfire again under anything over mild usage. Also even if the #8 plug is bad the carbon buildup is on the driver side butterfly valve so something is still wrong.

 

check ignition coil and ignition module.

 

Sorry, I was meaning the HT (high tension) leads - the leads to the spark plugs and the ignition coil.

Mark.

 

Probably an ignition problem.
Run it until it starts to backfire, stop, and change the coil while it's still hot (yes, I know it's new.)