My car runs good at 100 MPH but at 35 it bucks and misses bad. I changed the spark plugs and fuel filter with no change. I put the spare icm w/paste and now the teach is all over the place. It always worked fine . My cap is not that old and my wires checked out OK. When it runs it sounds like a sewing machine. A sound I have never heard from the engine before. Bad something having to do with fuel? Help please

If runs fine 100 mph it's not the fuel system. Sounds like yuor ign timing is off.

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Well I ordered a tach filter. Did it go bad or did I short it out somehow but not pushing the connector all the way in. All the wires are not frayed or even dirty. Time to check my timing too.

Tach filter has nothing to do with how it runs, only what the tach reads. Double check timing, fuel pressure, check for clean intake tract (throttle body, etc.), clean IAC, proper O2 sensor operation, and verify no check engine light.

I put a new icm/cap and rotor/coil/wires/spark plugs /fuel filter and it runs like a new car. I had 2 bad plug wires. My tach filter works too. All new parts are AC delco.

[This message has been edited by jim94 (edited 04-13-2014).]