Welll it was fun for a while.....until i got to a hill...
 

Im looking for my new found problem as well. Well today i went for cruise in the hill country (very hilly and very curvy...it was a blast!!). The whole time was a freakin Blast!! Just takin the fb arond sharp corners and pushing her hard. She was doing great!! UNTIL i reached a very STEEP hill (very fucking steep)...then she started bogging down in 3rd gear going uphill. I switch gears to see if that would help but it actually made it worse...so pull her over for a little bit but I do not turn her off (she is idling GREAT infact). After a quick break i am on my way again...then about 10 mins later she starts doing it agin on the smaller hills (and it only happens on the hills). So i pull over and i decide to change my fuel filter (Thank God for an extra one....). So i change it in like 3 mins tops, i start her and i am on my way...she IS GREAT NOW!!! until about 30 mins later then she did it (but not as viloently ..just smaller boggs in 4th gear) every now and then only on some hills. Now actually i do pull over again and look under where the filter is at then i see the fuel pump moving back and forth kinda violently (i dont think this is suppose to happen). Well i dont have the nessarry tools for a fuel pump removal in the middle of the texas hill country so i decided to head back home.....i fill her up with gas and i go on my way. Now on the drive back she actually was fine (though i did not push her hard like i was earlier but i was going on alot hills....she was fine. Tommorow morning i am gonna lift her up and check on that fuel pump to see if that movement it was making was the problem. BTW the fuel pump is only about 8 months old and she has a brand
new fuel filter. Any ideas guys what this could be!!!

could possibly be a rusty tank constantly clogging the fuel filter

Bad gas or stirred up crap in fuel tank, drain the tank and replace filter or take a chance and run it through this tank and change the filter. I would drain it completely especially if you have the drain plug in your tank.

If its near empty,pull the tank.
Its not hard to do,and youll be able to really clean out the crud,as well as clean/inspect the pickup sock filter.Realistically,not much should ever make it to the pump or external filter.That inlet sock is pretty fine mesh,but it could be ripped.

Also,it you still have a Nikki clean/check your little inlet filters at the carb where the feed line splits and goes to the two float chambers...under the banjo bolts.

Had the same problem with my 84 12A this summer, I go the car last Dec after it had sat for about a year only being started occassionally. Replace the fuel filter when I did tune-up. Was going up a bridge and it started to bog down in 3rd, I noticed that i had let it get below a 1/4. Got home and pulled the filter and it had all kind of crap init. I pulled the tank after draining it and had it cleaned out. Have ot had a problem with it since except now for the carb. I try not ot let my tanks get below a 1/2 on any of my vehicles. I love the hills around Cp Bullis. Was stationed at Ft Sam in 93-98 and took my 85 GLS-SE with the Camden supercharger up there and had a blast. Good luck on the car,Gary

is anyone going to address the violent swaying?
that's what has my attention.
but i'm stumped (besides crud in the line, but that doesnt explain movement).

well i checked it a little bit ago....and now its not swaying...WTF?!?!? i don't know what the was....

Yeah Marcello, those were some fun backroads yesterday....The way that pump was shaking(you can hear it rattle), it's almost like it was struggling. I'd vote for the tank pull and checking the fuel pickup.....If you want Marcello, you can roll by here and use my tools, jack, stands, whatever.....

re: pump vibration


...have you considered an Exorcism?

lol....well, I don't think that would do anything positive, lol....It wasn't crab walking or throwing up pea soup...hehehe...

give it a crucifix and see what it does.
if it pleasures itself you might want to get your ass in church.

any luck Marcello???