I have a 1995 probe gt and as of right now can not

I have a 1995 probe gt and as of right now can not seem to change votlage on tps to get it at 5.0 votlage with harrness disconted and key on(engine not running).I had gain on tps befor egr code came up.This seem's to be the answear to votlage cut out but what does the EGR have to do with the TPS? Also Would royal pruple 10-30 synthetic oil hurt car?Had done oil change when car had 117340 on it now it has 119768 on it.Could i change the oil back to regular oil with out hurtting engine?Scene i have change o2's and egr code came about i have blue somke come out the exhuast when I start from a stop and to a stop when low idle.is this cause by the egr being bad?