Took the the 03wrx out earlier, did about 30 miles called in at shop to get a snack came out and it took 3 attempts to get it started, when it did eventually start a flame about 6-8 ft long shot out of the exhaust and the bang felt like the windows had been blown out, has anybody else experienced anything similar.

 

Sounds like a flooded engine that spat a load of UL out the pipe!