void ADCH0_init(void){
    _ADSIDL  = 0; 
    //FORM<1:0>: Data Output Format bits
    _FORM0   = 0;         
    _FORM1    = 0;         
    //SSRC<2:0>: Conversion Trigger Source Select bits
    _SSRC0    = 1;       
    _SSRC1      = 1;
    _SSRC2     = 1;         
    _ASAM       = 1;          
    AD1CON2bits.VCFG    = 0b000;    // VR+ = AVDD, VR- = AVSS
    _CSCNA     = 0;          // 0 = Do not scan inputs. 
    _BUFM                       = 0;  
    AD1CON2bits.SMPI    = 0;      
    _ALTS                         = 0; 
    _ADRC = 0b0;  // 0 = Clock derived from system clock
    AD1CON3bits.SAMC    = 0b00001;  
    AD1CON3bits.ADCS    = 0b00000000;
    AD1PCFGLbits.PCFG0  = 0;    // Set AN0 as analog channel. 

   _CH0SA = 0b00000; 
    _AD1IE  = 0; 
    _SAMP   = 1;  //Start sampling    
}

It looks like I get less then 500 ksps, need to go through the code and figure out why.