As far as I know, she is the executor but I haven't seen the will. If she is the executor, does she still have power over financial issues?

If she is the executor and sole beneficiary, she has the power to do what she wants in conjunction with the will; however, if it said that, why wouldn't she show it to you? Get an attorney immediately. If you can't afford one, call the county probate office and see if they can direct you to some resources for help.

I have no means to get to lawyer or anywhere as my daughter took the car that was titled in moms and my name and transferred it to mom's name. Now, my daughter is selling it. She told me last night I have until Friday to buy it and I have no means to get to my bank which is 45 minutes away. In addition, she wants a credit mom and I have coming from the propane contract and lock box I cannot find. If I don't show with all three items; check, credit check, and lock box the deal is over. I am so frustrated. Does she have the power to ask for money from the propane company if she is executor of the will?

Can she do any actions if the death certificate has not yet been issued?

If the death certificate has not been issued yet, then she cannot be named executor (personal representative) of the estate yet. She currently has no authority to be making ANY transactions on your mother's accounts or property. You must get an attorney involved immediately to stop this.