dang thing still has the check engine light on
 

Hello all,
So here is my issue. I have the check engine light on. The codes are reading rich, and lean at the same time. I have set the timing to 5deg tdc. Set idle to 750. Ran sea foam through it. Checked 02 sensor it is reading a constant .6 vts if that means anything. I have tightened everything I can think of. New Plug wires, new plugs, new rotor, new rotor cap. Just re-adjusted the valves. Just re-adjusted the TPS. Just replaced the pcv valve. Still gets bad gas MPG compared to my old 89. Still has the check engine light on. Still for some reason somehow automatically drops the idle down to about 200rpms every time I set the idle to 750. Thoughts.... Anyone????:bang: