Not sure what you have checked.I've sent Bryan Herter all of my information for tuning my pcm. I have replaced the MAF and the temp sensor is functioning properly. Don't know what else to do at this point.
My past experience of similar issues.
Bad Coil Wire.
Bad Ignition Cable to Opti
Exhaust Manifold Leak - one time it was broken bolts
TPS is worn - replace it..
Bad EGR ..just plug the Vaccum line to check
ALSO you can disconnect the electrical connector to the EGR.
Hope these help