I have a descently modded silverado..it has speed density...it runs good one day and runs horrible the next???

Question

somedays it runs ecxeptionally..and some days it runs like ***...for ex: one day it will be 95 degrees outside medium humidity and it will run great....the next day it will be 95 degrees a little less humidity and it runs like ***..whats the deal????

Answer 1

Sounds like an ignition problem.

Check the plug wires, coilpacks or coil/distributor/rotor button (whichever applies), and spark plugs.

Answer 2

If it has a mass air flow sensor you might try cleaning the inside of it with spray choke cleaner. The little wires inside get dirty and affect the way it runs. Or it might have a map/baro sensor thats not working right.