1987 honda accord check engine light is on and itle is up and down

IF no light check engine on instrument panel , you need to check the fuel pump and crankshaft sensor ..

but drives ok other wise???? a KEY point.
yes. (i guess)
i can tell you , its ,
1: EGR stuck open. clean it.
2: ISC jammed, clean it.
3: or tming belt slipped. (hopeless till fixed, and power will be low all the time.
4 or tuneups never done. (spark , and filter parts)
5: is the check engine lamp out running?if not get the blink codes.
short list, the long list is 50 points.

there is a fuel injection module under the dash.if you,remove the module and check the circuit board it will have broken solders in it. our shop has fixed alot of those..a hayne smanual will show you how to take it out....sorry i do not reply.

It cuts down power by 1/4 so what do you think based on that?

check brake switch above pedal and brake light relay in engine compartment relay box.

Please see my tip at http://www.fixya.com/cars/r6053280-lights_out_lights_not_out_bulbs_ok . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

Sounds like ist starving for fuel, check line and filters for a block, then if no better chck carburation block or fuel pump.

Check the cooling fans. Relays and fuses are located in the engine bay fuse box.