INVESTORS RAISE STAKE IN PUROLATOR <PCC> Two New York management investment firms told the Securities and Exchange Commission they had increased their holdings in Purolator Courier Corp to 7.2 pct, from 6.2 pct. Mutual Shares Corp and Mutual Qualified Income Fund Inc said they were weighing offers to buy Purolator shares from PC Acquisition Inc, a unit of E.F. Hutton LBO Inc, for 35 dlrs a share, and from EAF Acquisitions Corp Inc, a unit of Emery Air Freight Corp. at 40 dlrs They told the commission they had bought their new Purolator shares March 25-27 for 34.875-35.250 dlrs each.