I have a 87 blazer with a 350 tbi motor. Im having surge problems at idle. I have replaced - O2,TPS, MAP, IAC, temp sensor and dont have any vac leaks. Its runs pretty good after it warms up but the idle is high at that time. Its driving me crazy and Ive spend a lot of money trying to fix it. I need help. I have read everything on the internet and its the same stuff.