With the '84, this could easily be a vacuum hose problem. The SI (I don't know about the others) had over 84 vacuum hoses, and two plastic boxes filled with little vacuum components. I took mine to two dealers and they both told me the same thing. When an '84 CRX gets a vacuum problem, it's time to throw it out. I replaced almost all the vacuum hoses, and tried a bunch of other things, payed a dealer over $1500 to try to find it, but to no avail. I wish I'd saved my money for a new CRX, or at least a new engine (without the vacuum hoses this time).