Question

Will the P1122 engine code prevent car from running on my 1996 GMC Suburban 7.4L? Car is messed up

Answer 1

P01122 TP (throttle position) sensor intermittent low voltage

No it does not prevent the engine from starting with P1122 this is considered a "D" type code condition.

Answer 2

P1122 CHEVROLET - Throttle Position Sensor Circuit Intermittent Low Voltage

Read more: https://www.autocodes.com/p1122_chevrolet.html