Ok well i have a 89/79 K5 Blazer with a 76 400ci. (406ci.) with my 89 heads and TBI on. I havent been driving it lately (past 6-8 weeks) and i noticed that under heavy acceleration in getting a miss/spuddering and it backfires through the TBI. Figure i need to throw new plugs and wires on anyhow. anyother thoughts? Also on a side note: 1.Anyone running the Holley TBI? 2.How much do you like it? 3.Noticeable power increase? 4.Can i Use Vortec Heads with my 89 intake manifold? Hey Thanks for any info u can throw my way.