Yes....and yes. They sometimes had "hunting" problems after reaching a certain speed with the car wobbling violently from side to side. They were also extremely lightweight when empty and any slack action could (and would) cause them to pop right off the track. And that happened on multiple occasions. My last encounter with these was back in 1999. I caught a 53-car cut of them headed to the Trailer Train plant in Augusta for scrapping.
To add a little to the story of the TTX 'Front Runners':
Part of the story of what happened to the fleet of front runner cars is told here; The tracking issues as explained by Posters above.
They (specifically, The Front Runners) developed a pretty bad reputation within the Rail Industry for their abilities to spontaneously derail; to the extent that for a time, the tale about how the Southern Pacific would accept them for delivery, but immediately unload them and return them to the Carrier they were received from, is mentioned in some of the information.
In the early 2000's they were accumulated and stored in Iowa, in large numbers. About 2002/2003 they were moved down to the St. Louis area and ultimately scrapped.
The National Museum of Transport ( in Kirkwood, MO.) St.Louis, Mo.
Has a Front runner in their collection:
TTOX #130059 "Piggyback" Flatcar 1984 Builder: United-American Car Company Four-wheel ¦Front-Runner² car; partial deck and fixed trailer hitch; loaded from overhead only; 28-inch instead of standard 33-inch wheels to lower car for better clearances.
The story was that one of the folks from the Museum saw the Front Runners stored over in E. Saint Louis and asked Trailer Train and one was donated to them. This was about 2002/2003.