This is ASB territory. The only times the party controlling the White House has not lost seats in a midterm in the past centurt were 1934, 1998, and 2002. They all represented unusual circumstances unlikely to be present in 1994: partial recovery from the depths of the Great Depression in 1934; the GOP's unpopular drive to impeach Clinton in 1998; and 9/11 in 2002. Moreover, even in these years the party in the White House just gained a few additional seats. (Even in 1962, with the Cuban Missile Crisis boosting JFK's popularity immensely the Democrats did lose ground in the House, though only very slightly.) Even if there were a "9/11" in 1993-4 and Clinton's popularity soared, all that would probably mean is that the Democrats would not *lose* nearly as many seats as they did in OTL.
For this reason, when I saw your subject, I assumed you meant (as you evidently did not, given your reference to Clinton accomplishing a lot more) what if Bush had won in 1992 and there had been a Democratic landslide in 1994. Even then, however, 356 seats for the Democrats is just preposterous. There are just *way* too many safe seats--even in "wave" years--for either party to have a majority like that in modern times.