74 Slant 6 Bogs & Stalls Under Load / 30 mph

The EGR will not affect idle/ low speed UNLESS the valve is leaking past WHEN CLOSED. Remove vacuum line from EGR, plug, and see if it improves. If you suspect it, make a block off plate (simple, scrap of strap and a bolt hole, some silicone sealer)

Idle mixture. You do NOT adjust idle mixture by "backing out" the screw and leaving it. You adjust it by 1....with engine otherwise tuned, AKA valve adjust if applicable, clean functional plugs, plug wires, cap, rotor, good (not sloppy worn) distributor, SET THE TIMING and not necessarily at "sticker" spec..................

Then with engine FULLY warmed up you set idle speed and idle mixture, and you may have to "go back and forth" because if the mixture is "off" far enough, it will affect idle RPM

So with all of the above, now adjust mixture. With engine at proper idle speed in park, adjust screw carefully "out" some (rich) then CW until engine "peaks" in RPM and then "starts" to fall off peak. Repeat to find "peak" you want it just slightly "lean" of peak without losing RPM so to say. Maybe about 1/8--1/4 turn CW from peak.

Some cars "like" to be set "in drive." Obviously THIS CAN BE DANGEROUS. Second person to hold brake is just about mandatory, unless you have some 100% safe method of chaining the car to a "tree."

Use a tach (dwell tach) or vacuum gauge or both to set idle. Max vacuum, max RPM

1...Generaly inspection, adjust valves, compression / leak down test
2....Replace as necessary plugs wires cap rotor etc etc
3....Adjust breaker points gap/ dwell if applicable. Inspect distributor for wear as well, and if breakerless, inspect reluctor/ pickup for strike damage, rust/ debri, etc
4...Set timing, test for mechanical and vacuum advance operation
5...Last set idle speed and mixture. Before doing, you should have inspected all vacuum hose routing and hookup, PCV, power brakes, EGR, choke pull off if used, etc etc for leaks and proper hookup.