My dodge is having trouble turning on. it take a while to turn the van on. we have changed many things that we thought was made it do this but it wasn't. what is wrong with it to make it not turn on right way??

If this is mainly a COLD start problem, then please start by checking the quality of the engine. Assess the compression ratio, the valve settings, the fuel settings and timings.
Make sure the fuel pump is calibrated and finally the battery must have good current on cranking the engine to allow the engine to fire.
I would recommend that instead of changing a part on assumption, please identify if this is a fuel or firing issue and proceed to check the section. Alternatively the scheduled maintenance must be done as required for the mileage clocked.