I have a 97 blazer with 260k Miles. It has a problem misfiring randomly. Some days it goes fine with no problem, but more often, it violently shakes when I get it over 1000 rpm. It loses power and if the windows are down, it sounds like there is compressed air blowing as the misfire happens.

Other info:
The exhaust smells awful, however i think that is due to a bad catalytic converter. It has been pulling the codes P0440, P0300, P0144, and P0143 as well. I am going to replace the cat soon, but other than that, I have no real leads.

I know the oxygen sensor that is throwing the two coeds is good, because i had tested it, but the computer doesnt pull the same info as it does. I think theres a bad wire somewhere.

In the last few years, the work i have done include, new tires, new(ish) transmission, fuel filter, air filter, radiator, front back brakes + lines + calipers and cylinders + rotors, steering arms (pitman and idler), front driver hub assembly, u joints, and i think thats about all.

I have recently done a small tune up as well including, spark plugs, wires, cap and rotor, egr gasket, pcv valve, oil and filter, and a helping of sea foam. That didnt help. Could it be a bad distributor? I feel like it isnt because of when it runs with no problem. Maybe a dirty throttle body, or bad tps sensor? i have no idea where to go now.

Please help.

 

double check wire order

 

Have you checked to make sure that all of the plug wires are connected? Or even check your oil and see if its getting burnt or low?