93 silverado missing
 

hi guys. finally got my truck. heres the issue. when i test drove it, i felt a shudder and thought tires etc. well turns out it's missing. some times bad, some times just a bit, then sometimes not at all. it even stall out friday morning till she warmed up. thinking dist. or wires,plugs? any other thoughts? it a 93 with a 5.7 with 190 on it.

This is ob1, is the service engine light on?

Ya, I had it tested first. Was map sensor. Replaced and reset. Then after 10 seconds came on and says 43. Electric spark control module failure. Looked under hood and can't find it on firewall by dist.

is it in block case on passenger firewall attached to the pcm? and i know there's one in distributor i was told that's kinda like a u shape. am i correct? i idles ok, but when getting to speed ( above 40) it shakes and surges a little. any ideas? gonna bring it in tomorrow but one place wants $50 to diagnose it.

anyone?

took air cleaner off to look at dist and pulled wire from coil to dist and alot of white powder fell out, thinking corrosion. and inside wire on coil side rusty inside. plus wire had a 1/4" long rub/burn mark in it. any ideas other then that to replace?

Sounds like you found it

No. Just tune up. Update Thursday night

Good luck!

Turns out it was carbon. On cap/rotor and distributor was loose.