Harrell, a first-year starter, threw five interceptions in losses to Missouri and Colorado and was briefly pulled in each of those games. But against one of the nation's worst secondaries, Harrell found his stride operating the Red Raiders' complicated passing offense, completing 31 of 40 throws.
Bret Meyer threw for 146 yards for Iowa State (3-5, 0-4), which lost for the fifth time in six games.
It's a good thing Harrell played so well, because Texas Tech committed 14 penalties and muffed two punts, allowing Iowa State to get as close as 28-26.
Bret Meyer capitalized on the first fumbled punt with a 10-yard TD run. Harrell answered on the next series with a 9-yard TD pass to Amendola, but the Red Raiders dropped another punt late in the first half, leading to a 23-yard field goal by Iowa State's Bret Culbertson.
Filani then extended an Iowa State drive with a penalty for roughing the kicker, and Jason Scales answered with a 5-yard TD run to cut Texas Tech's lead to 28-26.