Rep Power: 0

I'll attempt to break it down in short terms. I also have a list of attempts made to fix the issue.
Based on testing with the 1989 Honda Civic Hatchback DX
The engine is working off DPFI
NO CHECK ENGINE LIGHT
ECU IS WORKING

Symptoms...

Hesitation when accelerating
Sometimes idles strangely as if it's misfiring
Flicking throttle yields less 'power' than it used it, seems to misfire, but
checked distributor while idle and
flashes with spark plug testing tool were consistent
While accelerating, bogs down and slows even when gas pedal is floored

Replaced...

Spark Plugs
Spark Plug Wires
Distributor Coil
Fuel Filter
Fuel Injectors
Fuel Regulator
IACV

Tested...

Throttle body (Flicking the gas, the gate opens and closes normally)
Fuel Cleaner (2x)
Fuel Pump (40 Psi; 45 psi w/ Fuel regulator vac hose disconnected, also tested
while flicking throttle and psi went up to 42, but never dropped below 38
TPS (Unplugged and tested wires)
Throttle Cable (Is set, no extra slack)
Spark plugs (Used a spark plug testing tool, all were consistent flashes at idle
Checked...
Throttle cable (It's at the correct orientation, tried to adjust it but made it
operate worse, so its set back to default position)
Gas Cap (Seal is still good)
Clutch Cable (No grinding noise from clutch; cable is used but not out of use)
Air Filter (Clean, just replaced)
Battery (Gets the appropriate voltage, even when revving higher)

Any tips or ideas that come to mind are appreciated

 
Rep Power: 125

Sounds like you may have a vacuum leak. There are some videos that utilize a smoke machine to locate the leaks.