I have a 1990 integra rs, A few days ago my car started idleing really weird (cold start up idles at 3000 rpm, steadies out to 1000-2000 rpm. give it gas and it jumps between 1000-2000rpm.) I have replaced the IAC,map sensor andpcv valve. I dont have a check engine light on. i'm going to replace the coolant temp sensor tommorow. could this be a vac. leak?....can anyone help me? Joe

 

Could be a vac. I had the same problem. I looked around and found that one of the vaclines where cracked. (so small you could'nt see if without removing it and looking close)

 

You should probably check out all your underhood rubber, vac lines, water hoses etc. Maybe just replace all of it so you don't get any surprises