Lack of basic, preventive maintenance piled up over years. There is no "mysteries" in those FIRE family engines, threads like that are pretty boring and lame (crank no start, stalling, misfire, check engine, power steering cutting off, water in the boot/trunk etc.).
Yes, it is a little bit of everything. Probably swapping one part will not fix this car now (now it's too late).
Timing belt, valve clearance (all 8V engines), VVT operation (1,4 8V) spoiled due to dirt in the lubrication system (plus there is a loss of pressure, because an "o-rings" under the camshaft cover can leak), camshaft lobes "polished" a bit. Next of course the ignition system (old coil pack for example), fuel system (old fuel pump, dirty injectors). PCV "breather" system (contains TWO hoses and orifices to be cleaned). Oldest Grandes have improper water drains, water pours on the alternator, shortening the life (and bad alternator can stall the engine). Clutch switch (ECU uses this "signal" to control the engine). And so on...
Now tell me, how many of those terms above "ring a bell"...
