98 Honda civic shaking, car turning off

I have a 98 Honda civic, 100400miles, recently it has been acting
weird. the car will shake and the RPM gauge goes up and down.
Sometimes it even dies, when I try to start it, it will start but dies
again.
I took it to different mechanics but none could figure out the
problem. I finally took it to a honda dealer after my check light
engine went on. The check engine light was to change the Catalyst
converter, and he said it has nothing to do with my problem. the
Dealer said I need to change the spark plugs, wires and ignition
switch. I did all that but the problem is still there.
Can anyone help me out?
P.S: the starter, coil, distributer are all working fine.
Thanks!

 

I'd guess the igniter in your distributor was failing;the RPM(tach)problem
is a big clue pointing to that.

another thought;leaky fuel injectors;run 3-4 tankfuls of gas with injector
cleaner,see if things improve.(before you spend big $$ replacing them)


After that,I would check various sensors; crank sensor,knock sensor,speed
sensor,and most of all,you probably need a new O2 sensor.Generally,the O2
sensors are only good for 60K to 100K miles,and the secondary O2S could
wrongly indicate a bad catalytic,too.

 

thats what happens when you don't maintain a car. it puts a strain on more
expensive parts and they break.