1991 Honda Civic si 1.6 L manual transmission. Cars stalls while running and won’t start back up , I have to wait for two hrs to start again?

Take to the mechanic!!!!

The main relay. Search PGM FI

depending on how long run, how hot it got- symptoms are electrical relay, capacitor or coil/igniter problem. electric fuel pumps on last legs from overheating a second check. that vintage computer diagnostic is not as much info as later series- but code stored may give a rough idea of circuit- fuel or ignition. fuel circuit could be blocked vents, emissions canister clogged as well as fuel pump. 2 hour to restart is enough time for solid state circuit getting heat 'delamination' to close again, coils to cool down enough for internal short to open, Vapor lock in fuel line, filters, pumps to unlock, pressure seal to close again. A shot of ether in aircleaner next time it happens and try restart- if it runs a few seconds then implication is fuel system bad, ignition good. No start then means check electrics. Over heating and computer safety shut down for overheating until cooled down- that might happen on newer models with more safety/engine saving programming- but starter relay wired to neutral sensor, clutch sensor might have heat sense first? that means get out wiring diagram or check Honda Civic site for similar symptoms, service alerts. .

This happened to my Honda (1991), many years ago. Main fuel relay no doubt.

Hondas of this vintage were known for bad main relay and distributor. When the car stalls, check immediately for fuel pressure and spark. If both are not present, try replacing the main relay.

Just throwing random parts at a problem and expecting to get results is a REALLY STUPID way to work on a car, Skippy. If you don't know what you're doing STOP DOING IT! Take the car to a REAL, PROFESSIONAL MECHANIC and pay to have the problem fixed right the first time.

Replace the main relay while you are at it. It will be your last dart.

When a fault occurs with a car you diagnose the problem before wasting money on parts. I cannot imagine why you thought the starter and battery were at fault. In any case both items are easily tested with a £5 multimeter. If you have to wait for the car to cool down before it restarts that indicates an overheating problem. You need to investigate the cause. Or take it to a mechanic to save more wasted expenditure.