Honda: Check engine is On, air intake system, honda civic

Question
hi,
I bought Honda civic 98 EX coupe from auction, i went on repair. I fixed everything but when it comes to ignate the engine at first couldn't but after long try we finally worked on ignition. but the problem comes with the silence, It is Not normal raving is about 2.5rpm when started but after few seconds it goes up and down from 1.5 to 2.2rpms repeatedly, one of my friends disconect sensor from the Air intake system then the silence cools down but not Normal. I ve tried to drive it through Normal roads it shakes when driving below 50 to 35, but when i high way it drives okey with Litle shaking, I havent done anything yet...hope i can get help from you..so thet i will be aware of its problem
Thanx

Answer
Okay Henry,
If the Check Engine Light is on, you've got an emission problem.  Check the O2 sensor, you may need to replace it.  It could also be the Idle Air Control (IAC) valve.  This will mess with the engine's idle.  At any time since you bought the car, did the battery become disconnected from the car?  If not, then it should be for about 5 minutes.  This will reset the car's computer.
I hope I helped,
Barrett.