Thank you for quick reply-Have already checked egr,iac,tps,and fuel press.-all ok. can't find any vacuum leaks. will check reluctor but it appears to be just pressed on shaft-like yours it is either rusted or bronze coated on the end. in your later postings you mention distributor gear worn/sloppy-not sure if for your blazer or not. maybe i am breaking forum rules by going to you directly-first time for any forum-please advise me proper procedure

first check your EGR valve to see if its stuck open from any small carbon particles. you can blow it out with some compressed air. then after that check your fuel pressure to see if its within specs. also check for vacuum leaks. and lastly check to see if your reluctor has slipped on the rotor shaft....