I don't know if there is anything you can do about this without the WAD but whenever I start a game with my own IWAD, a few seconds later, the game crashes. Also, warping direct to some levels crashes the game immediately. I've attached 2 debug screen grabs in case it helps. The two look quite different though so it may well be different problems.
The first is after trying to start the game from the menu. This starts the game on map242 which is a simple difficulty selection map - no enemies and minimal scripts.
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The second is after warping to map07 which is a modified version of one of the levels from TQTrust (I think map07 in that WAD too).
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