First Lager Help.

So just did my first lager. It was good a little green/young but still was good, clear and drinkable. However, 2 big things with its taste I would like some help/ideas on. 1st, It had quite a buttery taste and almost heavy on the stomach once a drank a few pints. I did a diacytl rest for 3 days at 60 degrees f. 2nd is it had kind of a apple citrus tone to it I did not like. I used American Lager yeast WLP#840 which after using it I read leaves kinda small apple fruitiness which I really did not want. Here is my grain bill and fermentation profile.

9 lbs Pilsner Malt
Triple Decoction Mash
Recieved a 1.038 Gravity for 5 Gallons
Brewed with Perles and Cascade hops 1.043 after boil
Had trouble with chiller so it took me about 3.5 hrs to get down to 80 degrees.
Pitched yeast starter
In the Fridge set at 55 degrees for 9 days
Then Diacytal Rest at 60 degrees for 3 days
Transfered to Secondary
Then down to 36-40 degree lager for about 45 days (little over 1.5 months)
Kegged and force carbed in fridge.

You pitched too warm and the yeast made more diacetyl than they could reabsorb during the d rest. Try pitching a massive starter into wort 5-10 degrees BELOW your fermentation temp. Hold at 50-52 until you hit 1.018 or so and then d rest for 5-7 days, rack it and lager for 8 weeks. Then keg. Also, try avoiding American C-hops. Use noble hops with early additions only for many lagers.

Yeah. Sounds like you pitched your yeast too warm. And it wouldn't hurt to take the diacetyl rest up to 65 or 70 to get the yeast more active.

Maine is right above. Don't pitch until your wort is a few degrees below fermentation temps and pitch the proper amount of yeast.

Thanks for the helpful info. Also with using an immersion chiller it seems like it takes quite a while to get it from 100 down to 70-50 degrees. Any ideas or words of wisdom on how to drop it faster. Also as long as the wort is covered does it hurt it to sit out for a decent amount of time to chill? The last brew I did I actually froze multiple bottles of water, then dunked them in starsan and through them in the wort as well to try to cool quicker. is this a decent idea or is there something better. I know plate and counter flows are a lot better but I don't have money for one right now.

Stir your wort really fast in the opposite direction as the flow of water in the chiller. Make a steep vortex! Once down to 60ish, transfer to the carboy, put it in the fridge and set it for 48. Get up the next morning and pitch your massive but decanted yeast starter into the wort and set your temp for 50-55 -whichever temp you prefer in that range. Leave it alone until the krausen begins to drop and then take a gravity reading. Yada yada yada.