1997 silverado 5.7 liter bogging out need help please !!

[alexboston]

Please some one i need help!!! i bought 2 1997 chevy silverado pick up's both 2wd one is a 305 and the other is a 350 i paid to swap my 305 with a 350 vortec from the same year truck engine has 130,xxx miles i also installed the tranny. So i have installed patriot long tube header, and flow master true dual 40's with no cats!! i also installed a AL6 msd ignition and msd coil cap & rotor and 8mm summit racing wires with bosh platinum plugs. From a stand still when i go full throttle the truck would go to about 20mph and then cuts out it bogs out and then it picks up again? and some times when i punch it at a 20-30 roll it bogs out too. and when it dose not bog out it don't feel like its accelerating smooth like the engine is holding back? i installed 2 new bosh upstream 02 sensors hoping it will fix the issue but it didn't. The original truck that the 350 was in was a beast chirped 1 & 2nd gear accelerating great and it was fast but in my lighter truck it dose not? i read that i should put a EGR block off and have the truck tuned? i dont know what els to do nor what it could be? and i have called everyone i could no one can tune my 350 5.7? so i need help please its driving me crazy !!!

[Doug_Scott]

Couple of questions first.

 

What gear ratio does the truck that had the 350 originally have?

What gear ratio does the truck that had the 306 originally have?

When the engine was swapped, did all the peripherals follow the engine? Distributor for example.

Did the truck that came with the 350 have long tube headers, flowmaster 40s, and true duals?

Why is the truck that came with the 305 lighter than the one that came with the 350? 45 cu/in does not weigh enough for you to notice.

How long were these two trucks sitting before you bought them? Have checked the fuel itself?

What timing is the 350 set to in the 305 truck?

Do both trucks have same/similar wheel and tire size?

 

Adding long tube headers, with full dual exhaust with no x or h pipe, and running Flow Master 40s will very likely make the truck run lean due to the increased exhaust flow.

 

Have you checked or replaced the fuel filter yet?

 

If you are going to try new gas, do not buy high octane. Just use regular fuel.

[Duelin]

Did you do a "CASE" relearn after you swapped the engines?

[daxr]

With all the modifications, its probably not something as simple as a TPS going out...but that's worth a check.