High Intra cell failures on cells !!

Hi, I am facing a specific issue in our N/W. There are high Intra cell failures in numerous cells.
Situation:
Numerous cells have very high intra cells HO(s) happening.
We have switched off HR to HR intra cell HO(s). The ones happening are either FR to HR or FR to FR.
The count is as high as 3 to 4 thousand intra cells counts per hour (busy hours).
Now the problem is that the same is bringing down our HOSR (as intra cell success rate is counted in HOSR. Formula includes intra cell success & outgoing success over total pegs.
Many cells our N/W have high intra cell failures and no inter cell failures which is making HOSR KPI look really bad.
Parameters: Thresholds are with window from -75dB to -85dB & HO triggering at -90dB (town) & (-92dB rural). Rest parameters are in sync to support this.
The threshold for intra cell HO(s) to take place is till -75dB (means intra cell will only be initiated if and only if there is interference AND the level is at least -75dB.
CAN SOMEONE PLS ENRICH ME ON SOME OTHER INTRA CELL DECISSION PARAMETERS I NEED TO CHECK ALONG WITH REASONS FOR THE SAME.
One more catch point: Most calls are in idle mode band of 2nd best so idle mode interference can slighlty by taken lightly here in most cases.