Hunting down vacuum leak noise after EFI install

I finally got around to installing my Howell EFI last month. It makes an unbelievable difference in startup and driveability. I have blocked off all unused vacuum ports and stems. I have vacuum from the throttle body to the distributor (new hose) and vacuum from the intake manifold to the pcv valve (new hose, grommet, and pcv valve). Idle is good at startup, acceleration is great, and once warm the idle holds steady at 600. But, I still have a very noticeable vacuum noise during acceleration. When you back off the throttle it stops, and when the engine gets warm it is not as noticeable but still there. My EGR valve is still on the intake manifold, but the vacuum stem on it is capped. I wonder whether it is stuck open, which I understand would sound like a vacuum leak, but I also understand you get performance issues if the EGR is stuck open, which I don't seem to have. I have a 14" round x 3" deep air cleaner as recommended by Howell for the tbi. Anybody got any ideas? Thanks.

 

sounds to me like normal air noise/sound thru the open air filter.
You won't have a vac leak on accel, there is no vac on accel.
If the EGR were stuck open, it wouldn't idle, although cruise would appear okay.
there is a reason EFI air filters are in boxes/enclosures; to dampen the air sound.
just my guess and opinion.

 

That was my guess / hope, but its nice to have some confirming opinions. Thanks for the quick replies, now I can turn my attention back to fixing oil leaks instead of air leaks.

 

The pop off the air cleaner with the engine running, you will see the inlet for IAC valve/stepper motor. I believe is is the loud hissing noise you hear.