1989 Honda Prelude runs at hight rpms until warmed up

Have it looked at by a dealer,iam not sure here but i think you have a vacumn leak like the feed pipe to the servo split but really you need a mechanic who works on these cars day in day out and they will go straight too the problem for you

My honda prelude 1989 runs speed and later it will be slow and cannot run again.

Hi,
Sounds like your power brake Vacuum Booster has a leak. The vacuum
leak will cause the engine to lose RPM.
You should have it checked out as it will eventually start affecting your
brakes.

I would start with fuel filter. They are cheap and this is the problem they cause.

There is a warm up valve on the throttle body(should have 2 small coolant hoses). remove the valve and have someone start the car while you block the port to the valve on the intake. If that clears up the problem you can cut a piece of cardboard to mount in between the valve and intake.should straighten it out.

I had a similar problem. it would run great when the motor was cold until it started warming up. and then when i'd give it gas to get speed up it would act like it was either starving for gas or getting too much. I first started at the fuel injectors, pulled out the fuel filter and dumped it out, gas looked dirty so i replaced fuel filter and it didn't fix the problem, i then checked the fuel pump but it was ok. next i pulled the fuel tank and when i pulled out the pickup tube the screen at the end was clogged and their was chunks floating in the tank. Cleaned it all really well and havent had that problem since. hope this helps you

electrical issus. have you ever replaced the spark plugs and wires? distributer cap and rotor? might be time to do this routine maintenence.

I had the same problem on a Rover. There was a leak in inlet manifold that was caussing the problem.
To verify, spray some sealant to temporarily seal the inlet manifold .and the eratic idling should disappear for some time.
If it does, you know there is leak in inlet manifold which you can take of and refit with a new gasket.

Had similar problem with a Gemini. Try releasing the petrol filler cap before starting to equalise fuel tank/fuel line pressures.