I need help! My parents gave me a 1987 Samurai that was parked for about 12 years. For some reason it did not run and I don't know why. My husband has it running and we have done a full tune-up, replaced the battery, rebuilt the carb, replaced the radiator and water pump. Now it drives good cold. Once it heats up it sounds like it is constantly on the verge of stalling and once you gas it it istantly dies. Anyone have any ideas?

first things i would check would be valve adjustment, ignition timing, and go through that carb with a fine tooth comb and make sure you understand what you are looking at and that all fuel circuits are functioning properly.

I would replace all the rubber vacuum and fuel hoses too.

We did do all of the vacuum hoses too. What about the catalytic converter or O2 sensor? Could it be either of those you think?? I just don't want to dish out money if it will not fix it!!

i had this happen. not that good at idle and nothing when you open throttle.
probably a plugged main jet in carb.
possibly a mixture control solenoid either malfunctioning or a sensor not telling it to work.
there are good trouble shoot steps in the facory manual to check the carb., the computer, and the sensors(need a volt/ohm meter).
have you checked for trouble codes?
took me a while to 'sus it out.

just a thought

Didnt think of that, but it could be a clogged muffler. 

Tap on it, see if it sounds full or hollow.

does anyone thing that this is more likely in the fuel system rather than O2 sensor or cat converter??

any progress on repair?
just curious what you've found.

still nothing. my husband is set on it being the cat converter. i personally think maybe its timing. we just need to get the timing light. it almost seems to be running worse. frustrated.

Does it run fine once your RPM's are up when it's warm?  There are several extra solenoid's that open or close once the car has warmed up, one of them might be causing a problem.  Including one to adjust your choke.

OK guys, it runs cold, so the main jets are OK, also they did the tune up and
all the right repairs to an old truck that has been sitting for a long time.

The problem you are having is typical of a bad accelerator pump, which is
supposed to squirt gas into the throttle bore when you punch the gas pedal.

The test, with the engine off, remove the air filter, open the choke flap and
look down the throttle bore, you should see the throttle plate, now give the
carb a twist on the throttle lever, you should see gas squirting into the  bore,
and it should be a good squirt, not short, should not have air or bubbles in it.

If it's not there or really weak, pull the carb back off and check the plunger and
the circuit that leads to the nozzle where the gas squirts out, usually there is a
ball bearing that acts as a check valve, make sure it's in there or the gas will just
surge back into the float bowl instead of squirting into the throttle bore.
 
Was the carb rebuilt with a kit? often an old carb has been sitting so long that
the plunger is junk, happens from being dry for years, and you need to replace
the plunger

Wild