99 Marquis Misfiring After Cleaning Engine

[LieutenantCracker]

Last night, I cleaned my engine (1999 Grand Marquis) with cleaning/degreasing spray & "shine", and then it hosed-off w/ a fine mist of water-- The same method I've used more than once before, on the same car. I've had no problems in the past however, this time the engine is running very "rough". . . . . "Sputtering" (for lack of a better term)-- Maybe as-though it's not firing on all pistons(???)(I know very little about engines[!])
The major trouble is during acceleration (especially up hills). There've been a couple of times I thought she wasn't going to have enough power-- & just stall. But, once I get-up to my desired speed, she runs smoothly, as though there's no problem at all.
I was told that I probably got water somewhere where it shouldn't be [duh!] & that simply driving around for a while would "blow-out" &/or "dry-up" the problem but, I've driven her 85+ miles (mostly highway / 55-70 MPH) now; and now, when I'm stopped & in-gear it doesn't feel/sound AS bad, but the acceleration problem remains.
Also, during the "sputtering" / acceleration, the Check Engine light will flash until about 30 seconds after I've reached a continuous speed-- Then the light remains on: steady.
Any ideas? Any further diagnosis I can/should (shouldn't[?]) do. . . Bearing in mind my layman's skills/tools = having none beyond an ammeter & how to use it.
Thanks, in advance!
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Marijuana test

[way2old]

Have a core reader installed and see which cylinder is misfiring. Usually water will get into the coil and short it out. So you may need to replace coil and plug. You can try the plug first, but in my experience, it almost always takes a coil. Major auto parts stores will read the codes for free.