My 88 Civic DX is doing some very strange things. It starts just fine and then...sometimes immediately...sometimes after 5 minutes...sometimes after an hour of driving the engine begins to rev really high for a few seconds and then drops back down for a few seconds and up and down and up and down etc. Eventually (again, it's never a consistent length of time) it will drop back down and run normally for awhile. Please understand, I'm not talking about a normal erratic idle here...it sounds like a race car sitting on the starting block and I begin getting some funny looks from people. If the car is in first, second or third gear while this is happening it will accelerate without me even having my foot on the gas and it will maintain it's speed on it's own in fourth and fifth gear. I'm sorry, but my car does not have a tach so I cannot give you actual RPMs, but trust me, they're very high...like I'm in neutral and giving it a whole lot of gas. Strangely, I get no check engine light when this happens so I have no error codes to go on. After reading some posts from people having similar problems I have replaced the Electronic Air Control Valve (or Air Idle Control Valve) with no improvement (fortunately, I found the EACV at a junkyard...$3 instead of the $380 that several auto parts stores wanted for a new one). Interestingly, if I disconnect power to the EACV while this is happening the engine immediately drops down to what sounds to me like a very normal idle and stays there. I'm not exactly an accomplished mechanic, but, so far, I have done all of my own work on this car and have had nothing but success until now. Any help would be greatly appreciated. Any questions that you need answered to clarify the situation are welcomed. Thanks in advance.