Have a problem and its driving me crazy I hope someone can help out here...

When I go to accelerate sometimes its like there is a power level off or even a lack of. Sometimes it even surges like it is starving for air (old carb seat of pants feeling) and then cleans out and runs great. Almost like you are pumping the gas pedal when you take off. Other than that, truck starts right up first time every time, idles smooth, and at say 1/8 throttle it takes off fine but anything past that is where the stumbling problem is. There are no lights on to help guide me to whats wrong and none flashing on and off either ( i stared at dash the last couple times just to see if I was missing one)

Does anyone have any ideas where to start to track this down??

 

Verify Fuel system and Ignition system. Does SES light come on with key on, engine stopped? Got a scanner that will display live data?

Actually sounds like an ignition system malfunction, but could be lots of things. I wrote this below this morning for someone else but it applies to you as well.

Do ALL the tests in the Captain's thread on Fuel Pressure testing (top of this forum) exactly as described (not just part of them). You can borrow a nice high pressure fuel pressure gauge at no cost at many auto parts stores (deposit required). The other tools to block off fuel lines as described will need to be made. Post your results of all the tests. Please note that the upgrade AC/Delco MPFI spiders are known to regulate the fuel pressure to 58psi.

If all is well with the fuel system, move on to verifying the ignition system. Note that cross-firing inside the cap is a known issue with Vortec distributors. This can be caused by a poor-quality cap and rotor, bad plug wires, or the rotor not pointing where it should at the time the PCM chooses to fire the coil. For this reason we recommend a new AC/Delco cap and rotor be automatically installed. The way to check if the rotor is pointing to where it should, is by monitoring the cam sensor retard (CMP retard) live data on the scanner with the engine running. This should read 0° ± 2° or there is a problem. Lining up the rotor visibly with the #6 on the distributor gets you on the right tooth with the factory locked hold down, but that's about all it guarantees. A common problem that can cause the cam sensor retard to be off is a worn distributor gear (more common) and/or worn timing chain (less common).

You can check the distributor gear in place by holding the rotor down so it doesn't ride up on the helically cut gear, and then wiggle it back and forth. There should be zero play. Better yet is to remove the distributor and look at it. Timing gear slop can be checked by watching how many crank degrees it takes to move the rotor after reversing crankshaft direction.

Spark plug wires should be inspected inside both boots for carbon arcing, and checked with an ohm meter. More than a couple thousand ohms is not good.

Spark plugs should not have deposits on them and should be gapped properly. I'm going to go out on a limb and state that contrary to popular opinion, platinum-tip spark plugs are really not necessary. They extend the life of the spark plug, but good old fashioned ones will perform just as well (better) but for a shorter time. So spend your money as you see fit. Kind of like using full synthetic oil - I don't need it since I'm going to change in 3000 miles anyway.

 

I would start with the fuel leadown test https://blazerforum.com/forum/2nd-ge...eakdown-88305/ especially since you're not getting an SES light.

 

I would start by making sure the SES light is working. People do disconnect these when they sell vehicles. It was disconnected on mine.