They cheated with turbo restrictors on the works Celicas. They were caught in the Catalunya-Costa Brava and they were banned from the world championship in 1996. They returned in 1997 with the Corolla.
I'd much prefer to see them invest their time and money in ALMS than NASCAR and F1. The were rather successful with their TS010 in the 80's and early 90's, the GT-One came very close to win at Le Mans and all their xxC-V race cars were rather good performers.
P.S. Sorry for the previous posts.
The problem with the ALMS is that it is much less followed than NASCAR and F1. Toyota is much more visible in NASCAR and F1 than they would be in the ALMS or at Le Mans. The only problem is however, that they are not actually winning anything in these two series.