A 1977 Ford F150 may have had between 117 and 239 horsepower when new depending on the engine. One of the most popular engines, the 351 CID Windsor V8, kicked out 160 hp when it first came off the production line. A significant portion of this power will probably have faded if it hasn't been well-maintained with time. Even a well-looked-after model will see some performance losses. A tune-up might get most of it back, but probably not all of it.