Revs dont drop

Personally, the first place I would be checking is your air filter.

Hi,
Sounds like a tune up is in order.
You can mask the problem by changing the fuel filter and spark plugs.
Also there is a small adjustment screw at the throttle linkage. Open the hood and stand close to the battery. Have someone rev the engine and look for the circle or half circle looking spring like mechanism.This is your throttle. Take a small screwdriver or other wrench [ some have different adjustment screws] and simply turn the screw you will see as the adjuster in about 1.4 turn until you are happy with the idle.

Check that the choke accelerated idle cam is not stuck. Check that the throttle cable has not dislodged and the outer casing is riding on the bracket. Check that the throttle linkages are free and the throttle returns to the idle adjustment stop. If all these are correct, adjust the idle adjustment to obtain the correct idle speed. 700 - 800 rpm is about the right speed.

sounds like throttle cable.replace both, and you can adjust idle with adjustment knob look under carbs for round knob about an inch big.

Your idle air controller (IAC) is hanging up and it needs to be removed and cleaned-remove the throttle body and clean everything, it makes taking the IAC out to clean much easier. IF you don't have a check engine light, you will soon. Cleaning the throttle body, the IAC and checking the throttle position sensor is very easy to do on these engines, I have one with 178,000 miles on it.

If the throttle is "snapping" closed like it should but the RPM's are not coming down, it sounds like you might have a vacuum leak somewhere. I've seen the advertisements for this system but I have no experience working on it. Evidently, this carburetor has two throats on it. Use a feeler gauge and check the gap at the bottom or top of one side of the unit and then check the other side and see how close they are. I would assume that even though there are two throats, the throttle plates are controlled by one shaft and that shaft is controlled by the throttle and idle cables. If the two throttle plates are seperately adjustable, then they may not be adjsuted correctly. Go to Edelbrock's website and see if they've got a technical assistance phone number or whatever. Send them an e-mail. They'll know more about it than I would.

Good Luck
Steve

my 1990 toyota starlet idles fine its when i put my foot on the throttle it revs up then drops down by itself even when my foot is to the floor

Check that there is some free play in the throttle. When you twist the grip the first bit of movement should only be taking the slack out of the cable, in other words, you need about 1/16th of a turn of the grip before the throttle is actuated.
Also make sure the cable is routed properly - and check for any air leakage between the carburetor and the engine. With the engine running, if you spray WD-40 around the inlet manifold and it causes the idle speed to change, then there's an air leak.

I think a top end cleaning would be of value to you.

1. Remove inlet hose and clean with carb spray
2. Start car and rev up to about 2,000 rpm and feed more carb spray for a moment or two. It may not even want to run without a fight when you are doing this part.
3. With engine running, open throttle (wide open throttle) and hold hand over inlet and then take your hand away and allow it to flow again and release the throttle. Don't over rev it, you just want to create a vacuum state in the intake that will remove carbons, etc. Do this open throttle and cork it with your hand about 6-8 times. Then reassemble anything you took apart.

This trick removes stubborn gunk in the intake by loosening it with carb spray first and creating a vacuum to dislodge it. Expect a little black smoke when doing this trick.

Throttle positioning sensor, usually . Check for evident vacuum leaks.