So my thirdgen has had it's Vortec 350 for about a year and it has been running strong. It uses a TPI system from an 89 and the engine is from a 99 GMC Savanna 3/4 ton. Lately when driving the car, when I accelerate slightly harder than normal the car falls flat on its face for a second than picks back up. It is soooo jerky with acceleration. I have no check engine lights and the IAC TPS are recently changed (within 2 years). Anybody have any suggestions?

Part 2 of the question, I want to change the spark plugs (to try to fix this issue). Last time, I purchased plugs for the 99 Savanna Van (because Vortec heads). Should I be using the gap for the Van or for the Camaro? I also have a Crane Cams HI-6 Ignition Box and Accel Coil and some people say to gap the plugs wider because of that. What do you guys think about that? The Bosch Double Platinums I was looking into can't be gapped and are set to OEM specs, which is why I'm asking.

Thanks in Advance! Throw in any other info you think I should know!

 

Run the stock spec Vortec gap.
Do you still have the stock coil? I'm not a fan of aftermarket ignition parts for any mild builds. The first troubleshooting step I'd do is eliminate the Crane box and Accel coil.
One bad plug or wire wouldn't make it fall on its face.

 

Have used the box and coil for years even before the Vortec engine, I will try to bypass the box and see how that goes. I don't have a factory coil either. Gives me something to try though thank you!

 

Check your distributor gear. Just swapped in an l31 myself and it ate a brand new gm gear in 1000 miles. Endplay was off.

champion rs12yc or equivalent. I personally run ngk. .040 gap

 

Will check it out, bought a new dizzy a few days ago because I figured the cheap ebay one i spent 30 bucks on 4 years ago could cause a problem. Got an OEM style one. Will check all this stuff out change the plugs and dizzy then bypass the box and if still nothing I'll do the IAC and TPS adjustment stuff and check the fuel filter.