Hi I have a 3500 1997 stake truck with the 454 motor - dead stock. Lately it's developed a miss. My mechanic thought it was the cap since it was cracked - he replaced it - but the miss came back. I saw a plug wire sparking to the manifold, so I put in a set of plug wires. Still missing. So I changed the plugs. Still missing. Took it back to the mechanic after changing that stuff, and asked why the miss? The coil was good - then he spotted a loose plug wire. Fixed it. We thought we had it.


Nope. It idles just fine, smooth as can be, but under load it looses power and sounds like it's running on 7 cylinders. I dunno - it's not throwing any codes. Compression? Weak valve spring? Burned valve?


Any ideas?


Thanks G