White smoke pop/miss?

Ok so I'm having a problem that has me a bit worried. If I free rev over the past few days it will just give me a small amount of black or gray smoke followed by a lot of white & popping like a miss.It only does this when parked & I rev it.It has never done this before.I almost think that it is running a little different but can't say for sure. I Know my fuel filter is past due on change & I have a fuel leak @ my fuel filter housing not sure if it's the banjo bolt or if the filter head is cracked. But it's a 97 but I bought the 94-96 conversion kit from pure diesel . I've been meaning to install but I've been in & Out of the hospital. Dosn't really have smoke after start up or while driving. I have power that's not a issue. It's not throwing any codes starts right up.No coolant loss no signs of a blown head gasket.No wild or erratic RPMs will check injectors today& fix fuel leak if that dosn't help after the filter & etc where should I start? My p pump is stock I would hope I wouldn't have a bad p pump or burnt valve low comp etc.If ti

Sounds like it could just be pulling air somewhere.

Sent from my SAMSUNG-SM-G935A using Tapatalk

I'm thinking the timing slipped a little bit... putting the timing to about 1/8-3/16" advanced of pin timed should smarten it up nicely.. any EGT issues under load?