Rod Dreher, 'The Coming Methodist Schism", 3/11/2014, quoting an anonymous Methodist pastor:
One of my more moderate theology professors once told me that you could take the platform of the Democrat Party, take out the Party name and replace it with God and the UMC and most all of the faculty, staff, administration, and student body would whole heartily support it.
A literal global replacement of "Democrat(s)" with "God and the UMC" in the 2012 Democratic Party platform produces somewhat bizarre results — the first sentence becomes (with the replacement-site in bold face)
Four years ago, God and the UMC, independents, and many Republicans came together as Americans to move our country forward.
And the third paragraph (with pluralization to preserve grammaticality) starts
We Gods and the UMC offer America the opportunity to move our country forward by creating an economy built to last and built from the middle out.
But anyhow, the reason that Kim Temple sent me a link to Mr. Dreher's article was not to give me this opportunity for substitutional humor, but rather to point out the charming eggcornish blend "whole heartily".
"Whole heartily" is obviously a substitution for the more conventional "whole heartedly", which is an adverbial form of the phrase "whole hearted".
Constructions of the form ADJECTIVE BODYPART+ed are common in English: red faced, heavy handed, light fingered, red headed. The pattern is a productive one — I'm pretty sure I've never heard the phrase "magenta eyed", but I don't have a problem with it, and neither do plenty of people who have used it on the web. But many common phrases of this general form are quasi-idiomatic, so that "half hearted" and "whole hearted" work a lot better than "quarter hearted" or "third hearted" do.
And there seem to be some constraints on making adverbial forms of these expressions in -ly. My initial impression, which I don't have time to follow up in more detail, is that you need a body-part ending in /t/ or /d/ so that -ed takes the form [əd] rather than [t] or [d]. Thus "heavy handedly" works for me, but "light fingeredly" and "red facedly" definitely don't. There's also apparently some kind of semantic constraint, so that "red headedly" is odd because hair color just doesn't make for a good manner adverbial.
Anyhow, "whole heartedly" is just about as common as "whole hearted", but neither one is an everyday occurrence — about 0.01 to 0.02 per million:
The adjective hearty and the associated adverb heartily are much more common — about 4 per million for hearty, and 1 per million for heartily. So it's not surprising that some people lexicalize "whole heartedly" as the faux idiom "whole heartily", even though "whole hearty" is not there as a source. And indeed "whole heartily" is Out There — and it was noted in the Eggcorn Forum back in 2009.