Throughout the book, Dally is portrayed as a troubled and reckless character who often engages in risky behavior. His tendency towards violence and his willingness to take risks suggest that he may have taken a dangerous course of action without considering the consequences fully.
When Johnny and Dally are fleeing after the events at the church, Dally is described as being in a state of shock and grief over Johnny's condition. His desperate and chaotic state of mind could have contributed to his rash decision to face off against the police. Dally's loyalty to Johnny and the gang may have also played a role in his actions.
However, the book does not explicitly confirm that Dally intended to take his own life. It is also possible to interpret his actions as a reckless or impulsive act, driven by a combination of grief, anger, and the sense of hopelessness in the face of the situation.
Ultimately, whether or not Dally intended to commit suicide remains a matter of interpretation and personal analysis of the text. S.E. Hinton leaves the reader to ponder the complexities of the characters and the events of the story.