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Charge-air-cooler (intercooler) condensation is the signature driveability fault of the gen-1 3.5L EcoBoost: after an extended highway cruise in humid or damp weather, water that pools in the intercooler gets ingested on the next hard acceleration and causes an intermittent misfire/stumble and a brief loss of power under load. Ford issued a run of TSBs for exactly this pattern (12-10-19, 13-8-1, 14-0017, ASI-32227); roughly 100 F-150 EcoBoost complaint texts describe the humid-weather stumble or misfire, several while towing or merging.

Check — On the test drive get the engine to full temperature, then accelerate hard after a sustained cruise (ideally in humid or wet weather) and feel for a stumble or misfire; scan for stored misfire/DTC codes and ask whether the charge-air-cooler condensation TSB work (CAC drain/deflector, PCM recalibration) was performed.

A ticking/tapping or rattle from the engine's top front cover on a cold start (typically 2-5 seconds after a 6-hour-plus cold soak) is the gen-1 3.5L EcoBoost's early warning: it points at cam-phaser and primary timing-chain wear. Ford documented the cold-start front-cover rattle in TSBs 15-0131 and 18-2305, and a worn/stretched primary timing chain (DTC P0016, driveability faults, a dealer repair kit) in TSB 17-0026; owners report chain jobs near 2,500 dollars. 48 F-150 EcoBoost complaint texts mention the timing chain, cam phasers, or the cold-start rattle.

Check — Start the engine genuinely cold (parked overnight) and listen for a 2-5 second rattle from the front of the engine; have the codes scanned for P0016 or cam-timing faults and ask for timing-chain / cam-phaser service records. On a high-mileage EcoBoost budget for an eventual timing-chain job.