Help! I have a running problem!

[84hurst]

So I thought I had bad gas (gasoline ). After having the Hurst up and running after 10 mos., it ran fine for a couple of days, but all of a sudden, it started running like crap. It seems like it has a misfire, but it doesn't. It runs like crap only at RPMs lower that 1500. It went from a good idle of about 750 in park to about 450 w/ the engine shaking and dying. So, since I've gotten bad gas before, I drained the tank by disconnecting the fuel line that goes to the carb and letting it run w/ the line going into a gas can until the car died, and repeated this process a few times until the tank was empty. I went to the gas station and got $15 worth of premium and put that in. I still seem to have this problem. Normally, it runs fine after doing so, but it's still there. BTW, I am running an Edelbrock 750cfm carb. It seems to be very sensitive to the gas it gets, because I have had the same problem 3 times in about 5000 miles. Anybody else have any ideas what it may be? I'm getting very frustrated! Oh yeah, the fuel filter is relatively new as well. Thanks guys!

[PB86MCSS]

Double check over the whole ignition basics? Plugs, wires, firing order(I know it sounds dumb but we've all switched wires at one time), cap, rotor, etc. Timing correct? Any vac leaks?

This won't help but I traced down my LS's miss-fire behavior, was low battery voltage which made the EFI car run like total crap under any throttle.

[84hurst]

Double check over the whole ignition basics? Plugs, wires, firing order(I know it sounds dumb but we've all switched wires at one time), cap, rotor, etc. Timing correct? Any vac leaks?

This won't help but I traced down my LS's miss-fire behavior, was low battery voltage which made the EFI car run like total crap under any throttle.

I didn't check that, but only because I haven't messed w/ the plugs or wires, or anything ingition related in a long time. The only reason I suspect bad gas is because as I said, I have had the exact same symptoms before, and both times it checked out to be bad gas. Timing is correct and there are no vac leaks. Battery voltage is ok, reading about 14.4 during running and about 12.4 w/ car off. The other thing is that it runs perfectly OVER 1500 rpm, and total crap UNDER 1500. I'm at a loss. I'll be looking at it again tonight, though. I would like to make it to Solid Gold tonight if possible!

[purpl72olds]

I am intersted to here what you figure out. I pretty much have the same problem with my olds but i figured that the motor was just on its way out but maybe im wrong ? FYI, The car currently has a 403 with a small cam, performer Rpm intake manifold, 750 cfm Edelbrock carb, and Hooker headers. I also noticed the car has a severe stumble, sometimes even backfire through the carbs at WOT just off idle. Any ideas ?

[Memphis]

I'd check the coil and the ignition module. Either one will cause the type of problem you are having...

[84hurst]

Well, I figured it out...I think. My dad gave me the idea. Hit the bottom of the gas tank w/ a rubber mallet, so I did that. He also had to take off the fuel lines that go back to the tank at the fuel pump on the motor and blow into them, so I did that as well. It worked, so there must have been something clogging the fuel lines. It runs a lot better that it was, but there is still a slight hesitation right off idle, but that's something to look into at a later date.

[limpimpg]

check for vacuum leak spray carb with carb cleaner engine running and see if rpms raises.

[purpl72olds]

Memphis, should i have concerns with that stuff since it has HEI ? (sorry, reread my post and totally forgot to mention that, and its accel distrubitor with super coil on top)