I have an 86 T-type that will not idle properly. It stumbles up and down in closed and open loop, almost stalling. I have replaced the injectors, O2 sensor, IAC, all vacuum lines, MAF, fuel filter, plugs and wires. I reset the IAC and TPS to the correct settings. Observing the O2 readings I noticed they were consistently low around 300 in open and closed loop. In fact it threw a 44 code at one point. The IAC counts hover around 20. I checked engine vaccum with a gage and it was 15 inches of HG while the fuel pressure is 36 vac line off and 30 line on. Is this fuel pressure a bit too low? and why isn't the computer closing the IAC completely to compensate for the lean condidition? Where do I look next PUMP? REGULATOR? EGR VALVE?