Learn Spanish (Latin America): Iba a visitarte, pero surgió un inconveniente y choqué el carro. - I was going to visit you, but an inconvenience arose and I crashed the car.

This is the classic way to express an unfulfilled past intention! By using the imperfect iba + a + infinitive, you are saying you were going to do something. If you used the preterite fui a visitarte, it would mean you actually went and completed the action.

Could I say te iba a visitar instead of iba a visitarte?

Yes, absolutely! When you have an infinitive verb (like visitar), object pronouns can either be attached to the end of it (visitarte) or placed before the conjugated verb (te iba a visitar). Both are very common and mean the exact same thing.

Why do the verbs change from the imperfect (iba) to the preterite (surgió, choqué)?

This shows perfectly how the two past tenses work together. The imperfect (iba) sets the background—an ongoing intention you had at that time. The preterite (surgió, choqué) is used for the sudden, completed events that interrupted your plan (a problem arising and crashing the car).

The verb for "to crash" is chocar. Why is the "yo" form spelled choqué instead of chocé?