First,.. New guy.. Hello and great to be part of this site..
second... Please help!...89 burb, v1500, 5.7.. New parts: fuel pump, distributor, coil, spark control module, map sensor, temp sensor, EGR valve... Checked timing, fuel pressure, TPS, temp.. All checked perfect... Idles and revs perfect.. Problem lies when put reverse or drive, bogs down, sometimes misfires.. Put back in park, runs and revs fine... Also bogs with a/c on.,... Running out of ideas and parts to replace... Can't figure why it can't handle any load, but runs perfect in park.. Thank you for any help.. Kris

 

Have a helper monitor the fuel pressure when you shift it into gear.

 

Checked fuel pressure running, idling and throttle up, neutral and in gear....13psi... Never fluctuated

 

That sounds low but I'm not sure what it should be. Do you consider that to be adequate fuel pressure?

 

Book says spec is 9-15... From what I've read, anything lower than 11 is problematic.....

 

Is that a throttle body or a fuel injection system?

 

A throttle bottle injection

 

I didn't realize that throttle body injection required that low of a fuel pressure. That's not much more than a carburetor takes.

 

The multi port injection is like 60 pounds or something like that, but this one only has the two injectors..I thought it would've been higher also

 

Yeah me too. Good luck on fixing it and let us know what you finally find.