Most likely the problem with your oven is a bad igniter (the part you called "heating element").
Let me explain how it works:
The igniter is wired in series with the burner valve. When the thermostat calls for heat, line voltage is applied to the circuit. As the igniter begins to glow, the current increases. The current flow causes the valve to open when the igniter becomes bright red (almost white). Flat igniters operate from 3.2 to 3.6 amps. In your case the current is less or about 3.2 amps and it does not open the gas valve or opens it only a little bit letting very small amount of the gas to come out which is not enough for the igniter to light up. When the oven door is closed, the gas is accumulating inside the oven and if the igniter is on, causing a small explosion, which you heard as a "WHOOOMP".
Most likely replacing the igniter should solve the problem.
- The part number for the new oven igniter AP2634719