It sounds like one of the SCRs is misfiring under load. In the EV1 manual look up symptoms 1E and 2B. Since the #2 and #5 are new, check the 22 and 25 RECs. Notice that it says the 25 can check good but still cause the #5 to misfire under load so that may be the next part to try. If any of the SCRs misfire it is going to shut down with the pmt, like what is happening.