My 84 coupe has the usual 5.7 crossfire set up. I am ok with it, and I just did a complete tune up. Wires, plugs air filter, PCV, fuel filter, etc. This did a little better for the engine. But, there seems to be a stall when shifting. Just driving around under normal load all is well. But stomping on it, it hesitates and the motor makes a missing sound, like its bogging down. If I let off the gas a little, it will shift and go. Is this the high rpm face plant people are talking about? If so, how do I get around it? New crate motor from GM, cam and fuel rails....

 

You should ckeck your throttle-body bushings. They often wear out causing a vacuum leak that creates the kind of hesitation you're describing. Could also be the fuel pump. Typically fuel pump problems first manifest themselves as a problem when stomping on it because the pump can't keep up with the additional demand.

I would first check fuel pressure. It should hold steady even when you full-throttle it in 2nd or 3rd gear. YOu'll need to rig up a gauge to check it while moving. I did mine by putting a "T" in where the fuel filter is, and running a line up to a gauge my buddy held from the passenger seat. Your redneck solutions may vary.

For the TB's, take the air cleaner assembly off entirely. Open the throttle so you can grab the butterflies on each TB. There shouldn't be any slop in them. If you can wiggle them up and down then they need re-bushing. Also, if they're really bad you can look at the end where the butterfly-shaft goes into the aluminum TB body. Should be any slop there.

Lastly, you may need re-balancing of your TBs with a gauge. There are a couple threads about doing this procedure. Search around.