I have wood lap siding on my house and have been going room by room tearing out sheet rock and running new wiring and then using batt insulating from the inside. On the outside I and using 1" foam insulating and then using heavy mill plastic on top of it then using hardi-plank siding. My question is, is using plastic as a house wrap a bad idea?

Absolutely. Doing so creates two vapor retarders. House wrap is designed to allow the passage of moisture. Your plastic film will not do so. Bad idea.

Amen to what Rich said.

Wrapping the outside/cold side with plastic will trap moisture inside the wall cavity encouraging condensation, soaking insulation which reduces efficiency and causing mold growth.

Ditto the first two postings. Really bad idea, for all the reasons listed. You are creating a disaster, unless you live in the tropical rain forest, and maintain an air-conditioned interior all year around.

Let me elaborate. Lots of things, such as cooking, showers, breathing, sweating, etc., etc., produce moisture inside the house. This moisture wants to leave. Vapor barrier, such as plastic sheeting, batt insulation facing, and similar materials are used on the INSIDE of the wall system to prevent this moisture from getting into the walls. Any moisture that does get into the walls needs to escape to the outside. Vapor barrier on the outside prevents this, and traps the moisture from leaving. When it is cold out, it is worse, because the moisture will condense on the outside vapor barrier, just like water on the outside of a cold glass. This problem is serious enough that if you have applied plastic under your exterior siding, you need to remove the siding and replace the plastic with tyvek house wrap or similar breathable material. If you don't, you will see damage. I have seen as much as 3" of water standing in the bays between studs when this was done.

Plastic or Visqueen is the worst exterior applied product you can install on wood frame construction.. Tyvek is probably the best exterior applied product to keep exterior moisture off your sheeting, framing, insulation and drywall. I just finished an complete exterior renovation of an apartment complex here in Central Florida due to the General Contractor being allowed to value the Tyvek out of the job in lieu of using kraft faced lathe for exterior applied stucco. Stucco is a cementious product that allows water to weep it's way to the sheeting, studs. insulation and finally your drywall and the results were basically a sick building with mold and mildue growing on the inside and outside of the exterior walls. What a mess General Electric owned the project and had to relocate each tennant to avoid the pending lawsuits.