Engine ran fine. Stopped at gas station and engine turns over but won't start.

Spark.... Fuel pressure.... Compression!!!!!????

Turn the crank backwards and then forward , mark the crank pulley and measure the amount of free play. Post that along with , as pushrod mentioned , the compression , My guess is , if you turn the crank backwards rapidly , you might hear a ratcheting sound and then , if you do , go try to start it. IF it starts , you got your answer! Seriously , had one drop dead on me (customer drove in and shut it off and it wouldn't re-start , I checked chain free-play , then yanked backwards on the crank pulley and heard the ratcheting noise, got curious and turned the key and it started right up!! Drove it inside the shop and replaced the chain etc. CRAZY!..

ANSWER by Thomasdolby456, October 20, 2016 I've got a 93 Century, 3.3, with 72,456 on the clock. I'm retrieving a 22 (low voltage to TPS) and 44 (lean exhaust) from ECM. Last 2 months I've been dealing with intermittent stalling, but now the car won't start. It used to restart upon cooling off. I've changed the ICM, ignition wires, bad coil, new plugs, new PCV, CKP sensor, fuel filter, battery. I'm ready to junk it, it could be the TPS or ECM. But it's a crapshoot. I doubt it's blown gasket, no leaks detected, oil cap and radiator cap look ok. Can it really be the TPS or ECM ?