Van turns over but won't stay on

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Hello my 2005 dodge grand caravan was recently broken into, my steering column was destroyed basically, my mechanic replaced the entire steering column with the column of a 2005 Chrysler Town & Country with keys & all, my van will turn on but won't stay ON, it's like is stalls out maybe not getting gas. Please any input would be greatly appreciated. It's the only vehicle I have and really need it to get my kids around. Even the mechanic is at a loss I think. Thank you!