I recently picked up a 93 Accord DX and have a few issues. First, it seems to be overheating. I'm 99% sure it is not a head gasket that is causing this issue though. It does not have coolant in the oil or smoke coming out the tail pipe. It does, however, warrm up very quickly.
I started it tonight and went for a little drive to see how fast it got warm. I had heat blowing out the vents and the temp guage mid range in about 2 miles. The temp guage stayed at mid range until I hit about 3 1/2 miles. At that point, it went up to just below H and pretty much stayed there until I got home(about 4 more miles) Speeds ranged from 25 to 50 mph, the cooling fan works as far as I know. One thing I did notice is the temp guage drops when accelerating. Once I got home, I pulled into the shop, put it in park and revved the engine to 3000 RPM, the temp immediately started to drop, almost to mid range on the guage with 15 seconds of holding a steady 3000 RPM. As soon as I let it go back to idle, the temp started climbing. I also noticed the upper radiator hose was extremely hard, i could hardly squeeze it. The lower(from the radiator) was the just about the same, a little softer than the upper.
Could this be a water pump issue? Stuck thermostat?

Second issue is idle speed and quality. Upon starting the car today, the idle went up to 2000 RPM and stayed there. I revved it a little and it then started to surge, 2000, drop to 750, up to 2000, etc. I shut it off, restarted and it went back to 200 and stayed there. I then decided to drive it to see if it would clear up. It did, kinda. 1 1/2 miles down the road, I came to a stop sign, the idle was down to 750 and surging slightly. I also had a slight off idle hesitation while accelerating away from the stp sign. These idle issues seemed to dissaper the warmer the engine got, by 4 miles into my drive and the temp guage near H, it idles perfectly and had little or no hessitation on acceleration. What could be the cause of this issue? PCV valve is good, it is new.

Sorry for the long winded post, I just wanted to give the best info I had to help diagnose these problems.

 

The first thing I would do was change the rad cap and flush the system,If the coolant does not look like it's been changed recently,if the thermostat is sticking it could be the reason for the rapid drop in temps.when it opens. if after doing a flush or thermostat change does not cool it down,try removing the rad. and cleaning it your self,I just cleaned the one on my Diesel,I soaked it with a good cleaner ,let is sit for 10 min. then sprayed it with a garden hose on high .I did this several time and do it from the back to front to dislodge grime and bugs,you will be surprised at the stuff you can flush out,my temp dropped 15 degrees on my Truck,good luck.

 

As for the idle issue,I would try cleaning the throttlebody with a good throttle body cleaner,not a carb cleaner,follow the label,sounds to me like it's sticking and when warmed up it lets loose.

 

I agree with bucwheat that you should try cleaning the trolllerbody.may be then it would be fine.

 

The Idle issue 99% of the time on hondas cause by the idle control vavle malfuntioning or leaking coolant.. the IAC location on the 1993 will be located on the intake plenum there are 2 pieces to it looking at the intake from the front of the ca about the center of it side facing you aka front of car right side have hoses coming from the thermostat area same place the second part should be to the left of the other connected via hose too but this one has a plug for the sensor on it fairly cheap to replace, if leave disconnected lower idle with idle set screw too 500 rpm on this car with the sensor disconnected suggested by Honda for sensor removale and testing. might help fix some of your getting hott issues too, also try bleeding the air out of the cooling system for one they actually had a problem hense the bleeder on top of the thermostat housing to bleed the air out the infamous japan air bubbles most have only heard of. the idle for this car suppose to be at 750 rpm + - 50 rpm window, the thermostat would also replace it they are very cheap. it it was the water pump you should see it dripping aroung the timing belt cover water pump located in side the cover, would be very noticable, Hope This Helps You, Good Luck & God Bless