Hi my mitsubishi express l300 1985 automatic is causing me many problems.

when i drive it sometimes backfires badly - like an explosion. when i dont have the revs up it also runs dirty and does smaller backfires. when i am idling it runs dirty and miss fires also and sometimes stalls.

it also doesnt start sometimes when i have driven it then stopped briefly. i have to wait 20 mins to start it again. the engine is not overheating and the petrol pump is working properly putting fuel into the carby. i also had new points put in and a new condenser. she also gets floded sometimes. should i try getting a new coil?

i have a hole in the exhaust - could this be causing some of the problems?

i also dropped a valve in the head a few months ago could this be causing the problems?

recently she is struggling when going up hills? and also i lost all power and the accelerator went floppy the other day and then i regained power after a few seconds?

do you have any answers for me please?? it would be much appreciated

thank you