Timing potential problem

Just bought this car it is the HF model with rebuilt engine. It had a number of small problems one being after re-indexing the timing belt. I now have initial timing set at twelve degrees btdc at 600 rpm runs very good now with good power for an HF model. However, after setting initial timing properly along with the cam gear set right it seems there is no timing advance when revved. The car has a brand anew distributor and looks like correct one could this be a faulty ECM? I reset ECM pulling hazard fuse for thirty seconds no change. The guy I bought the car from said gas mileage dropped from fifty five to forty five mpg, although I cannot verify that yet. Also replaced PCV valve it was stuck. Installed Ngk v-power plugs there were Autolite plugs in this engine. Is there a way to test ECM for timing advance?