my car has a tendency to run ok for a little and then go through phases of poor performance driving,I'm not expecting much 'cause it does have unknown milage(approx 100k) but it shows its true colors now and then,it has low vaccume due to the rings and probably various gaskets that might have something to do with it. when it runs bad it seems like you can feed it all sorts of gas,and it uses it,but it only picks up at its own pace.the engine sounds different too, it just revs and and doesn't go anywhere like some one swaped the torque converter or somthing.it could be anything but I'm pretty sure it's that carb. or maybee its just possesed.....oooooh

 

Well, your post has told me absolutely nothing to help me diagnose your problem. Since you are balming your carb, i'll blame your...rear defroster. Yup. I bet your rear defroster switch is bad, occasionally randomly turning it on causing a large voltage drain on your alternator which reduces the efficiciency of your ignition system, which causes a loss of power.
Now if you want to refute this diagnosis you can give us exact symptoms as well as what you've checked and what you know about the car.
...ed

 

If the Car is revving and not Going anywhere you are prolly low on tranny fluid.




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85 Z28 - Daily Driver
60 Ranchero - Project ( Money Hole )

 

Can't tell nothing without knowing what the ECM is seeing (beg borrow or steal a scan tool).

But remember the old mechanic's rule that 90% of carburetor problems are found in the ignition.

A quick story- my brother bought a boat recently with a carbureted 350 in it. Wouldn't get out of it's own way under load. Turned out the ignition coil was fried (actually leaking coil oil out the top of the coil tower!). A $20 ignition coil later and it was stomping some of the slower Baja speed boats in his local marina- 52 MPH top speed!

 

sorry fella's,this really did'nt belong in the carb board after all. I tested my HEI ignition and found the pick-up coil to be out of tolerance 0 ohms(good: 500-1500 ohms).I dismantled the distributer and basically poured the old coil out.the symtom prior,was the car would drastically lose throttle response when the engine was warmed up,and gain some performance back for short amount of times.leading me to think it was Q-jet mood swings.

 

You see! I TOLD you! I TOLD YOU! I TOLD YOU!!!!

[jumping up and down hysterically]

Glad you got it naled down, anyways. Nothing like finding out that a problem is only a $25 ignition part fix to brighten anyone's day!