How would the following affect the calculated value of neutralizing power of antacid (make it higher, lower or no effect)?

[The lab uses the back titration technique]

1) The solution mixture of reacted antacid and excess of HCl spattered out the flask during boiling

2) The endpoint was missed because NaOH was added too fast during titration.

3) The mixture of antacid and HCl was heated too long so that some HCl escaped from the solution

4) Some antacid solids were not dissolved in the presence of excess of HCl