Honda Repair: 1993 Civic LX power loss, gas milage, maintence

Question
I have a 93 civic LX w/ 207,000.  All maintence is up to date. I purchassed this new. The car had been running great. My gas milage had been 37 mpg w/ a/c on.  I was on I-75 going 80 mph when the car started slowing down. The car now has no power below 3500rpm. It also idles very low when warm. Gas milage is very poor. I replaced the coil and igniter in an attempt to fix w/ no improvement. There are no codes in the computer and check engine light is not on. This just happened out of the blue and I have no more ideas. Can you help?

Answer
Brian:
I would go through and check the ignition parts; plugs, plug wires, distributor cap and rotor. You should also check the ignition timing to make sure it is correct.
Good luck.
Bill
Follow-up...
Since that all checks good, you may need to check the fuel system, it might be a good idea to change the fuel filter.
Other things you may want to check is a plugged catalytic converter, to do this you can remove it and put a temporary connector in its place. This can be a pain since the bolts are rusted on. Other than that you can check the transmission.
Hope this helps.
Bill
#### 2nd follow-up ####
You can take to dealer and not authorize the work, only authorize the diagnosis and you can take it from there.
Just a thought cause I've done this before when I'm stumped.
Bill