If it's not fuel then it's a volumetric efficiency issue.
Try this: Bring engine to operating temp. Place vacuum gauge to read manifold vacuum. Record vacuum reading at idle in park or neutral. Bring engine rpm up to 2500, hold, read vacuum gauge.
Is the vacuum reading at 2500rpm the same or higher than the reading at idle? It should be same or higher.

If it's lower at 2500 rpm then it's a breathing problem.
#1 Cam timing is incorrect. Remove valve cover, bring engine to TDC on exhaust stroke (360* from TDC compression stroke) using piston stop. Don't rely on dampner markings or timing chain markings.
Inspect intake and exhaust rocker action as you rotate engine back and forth no more than 10*. Are both valves being activated? Exhaust closing and intake opening?