Bucking/Engine problem

[lux]

87 fiero gt

My car does this weird bucking problem when I'm at idle.
I cleaned out most of my car including the EGR valve.
I replaced a ^%!) load of things already that could have
been the problem but it continues. (I replaced plugs,
map and throttle position sensor, fuel and air filter,
dist module, and rotor.) What the hell am I missing? 

[Fierofool]

First, I'd like to welcome you to our forum.

I would guess that you don't notice this at road speed.  Taking into consideration the things you've already replaced, I would look at 3 areas. 

Check out the plug wires to be sure they are in the right order, and that they are in good condition.  Occasionally a plug wire will chafe or burn on the front side of the engine, where you can't see it.  You can determine which cylinder is missing by removing each wire in sequence, from the distributor cap.  It could even be that plug wires might be crossed.  I have experienced the same problem you have, and found I had swapped 2 wires.

The other possibility is that you may have a clogged or malfunctioning fuel injector. 

[RobsFieros]

Did you check your timing?

[Tha Driver]

I read somewhere that a bad tach filter can cause this problem. Is your tach jumpy?
~ Paul
aka "Tha Driver"

The United States is the only industrialized nation to *outlaw* hemp production.

[watkins23xl]

Ok, are you talking about when you are powering, then let off on the gas , and just between powering and giving the gas, it does it!?  If so, then check your vacuum lines.  Had the same problem in three of mine! Yup, same thing in all three.  cheneyc@bellsouth.net if this fits the problem, kind of, and I will explain it further.  If this is not your problem, then just delete! Lol
Take care,
C
Actually, on my first one, the line was crimped