93 Geo that only runs for 4 min dies and will not after

check fuel pressure could have clogged fuel filter or bad fuel pump.

this is a very old car, I restored a 91,
took me 1 month hard labor to get 91 to be
reliable and safe.
the first step is to find out if the car is a 8valve or 16,???
then get the book on it as most mech, in you area have not a clue how to fix these very old and odd cars. old electronics called OBD1 and suzuki support on this old EFI system is zip .
ever do the 60k tune up?
ever replace the timing belt, if not why not? it will slip and the engine
dies.
sounds like you are losing spark or fuel.
only conducting tests, to find the cause, will work , guessing is futile.

If you own this old car, get the FSM.
then when getting help from a mech, you have the book in hand.
and he can then use it.
In a pro show (ASE) they have alldata dot com and can use that.
or
this.
http://www.fixkick.com/

additive? for what reason, for stalling? or just for fun added.
you didnt say.?????
if it was for bad running, did you read the container, ?
and add the correct amount on a full tank of fuel, if not , then you may have added too much, some additives are very bad,
next time use Techron fuel additive, (if you feel compelled)
if the car runs bad no fresh fuel, and all 4 sparks are fouled.
no additive is best. fouled sparks are from other reasons.
50 reasons. and not one is cured by magic in a bottle.
I run Chevron fuel in my car, so adding more benzene is of no help
ever.
you said plugs, that to me means, (????)_all 4 are fouled.
4 plugs changed, where they spec type spark plugs, J plugs.
and were the gapped to Geo Storm spec.
if new plugs foul? that means (all 4?) means its running rich.
top reason for rich are:
1: thermostat missing or stuck open (engine never reaches normal temp)
2: Sensors reading wrong,
The Check engine lamp, what does it do.?
Is CEL light glowing key on,. then out after starting, (no? then pull the DTC codes and read the problem)
too high fuel pressure, ask your mech to measure that. or DIY.
ECU stuck in limphome mode. check DTC codes for reason.
Dead , bad or weak sensors.
leaking injectors
Ask any ASE mechanic, to just diagnose the problem.
then you have your answer. but many shops never seen a GEO ever
and have no documentation. on these.
how ever alldata dot com has it.

First look at fuel pressure pump jam

try changing the fuel pump relay...its on the driver side fuse box near the brake line

ignition module

check gas and filter

Get a voltmeter, place the positive lead on the lug off of the alternator, or on the pos. battery terminal when running. ground to chassis or body. ALTERNATOR VOLTAGE: 13.5 or higher at 1500RPM is minimum

MAP SENSOR.

Ussually with the Preludes the main relay for the fuel pump needs to be replaced. One that i havent seen posted yet is the 'Coolant tempature switch' near the distributor some times becomes faulty. Cheap at local auto parts dealer.