86 el camino stalls under load - 1986 Chevrolet El Camino

As mentioned above, engine could be starving for fuel; but
also consider ignition system - as engine makes more power, maximum cylinder pressures increase. A higher spark voltage is then needed to ignite mixture (at a few degrees before top dead center... top of piston travel).
If coil is weak, plugs fouled, or plug gap too wide, adequate spark may not occur. This may cause missing,
loss of power, sometimes backfiring (backfiring may occur if timing is off, or intake valve leaky, also). If you replace the fuel filter, 'kit' the carb, but problem remains,
look to ignition system.

Diagnostic process - put a fuel pressure gauge in line, where fuel line enters carb. Rig so can see gauge, while driving. Have a passenger watch fuel pressure as you drive; especially while accelerating. If fuel pressure drops during acceleration, then its either fuel pump or filter. If pressure remains stable, consider carb issue.
If possible, test with exhaust gas analyzer, while engine
under load (possibly at an emissions test place). If lean under acceleration, its a carb problem. If not, look at
ignition system (emission test diagnostics should help here, also). Oh, and one thing I did once.... forgot to release parking brake..... duh.

Best of luck !