FAILURE SEAT TOLEDO GLX 92

Hello. I have a 1992 Seat Toledo 1.8 GLX. My problem is that it starts perfectly when cold, but after running for a while, it starts stalling. It's been in the garage for almost six months, and they've checked it from top to bottom without finding anything wrong. They've replaced the fuel pump, a sensor, the battery is new, and the wiring is theoretically fine (by theoretically, I mean that's what the mechanic told me, but they say it's most likely an electrical fault). At first, we thought maybe there was some water in the gasoline, so we added a product, but nothing changed. I wanted to know if anyone has experienced something similar (since I've been told these cars have had many problems, although mine had never had any issues...) or if anyone knows what might be wrong.
Thanks

Check the power supply to the engine control unit; these units are usually powered through a relay (called 30) that is usually located under the steering wheel.

Many cars have this problem, and the issues are different in each case. The relay that titinemo mentioned is one of the factors, as it's a tachometer relay with a built-in circuit responsible for distributing the spark and current to the fuel pump. It's somewhat complex, but also check for air leaks in the fuel injection system. Try a direct fuel connection; bypass the system and connect wires directly to the pump. Finally, check for spark continuity. If you have an ignition module, it can sometimes cause problems, especially when it's inside the distributor, but simply removing it and placing it further out can be a problem. It might be causing an intermittent short circuit. Test it and let us know so we can continue helping you.

I also have a Toledo 1.8 IGL and something similar happens to me. It starts right up, but after driving for a while, if I stop at a traffic light, it revs up, and if I stop, it's incredibly difficult to restart. I'm hoping someone can give me a solution; it's driving me crazy! Cheers to all.

Check the temperature sensor