I'm trying two adress two separate areas of clunkyness with one houserule here:

Rule: Once per turn, when using an Investigator Card trait that requires an Action Point for activation, the investigator may consume a movement point instead of an action point; as part of the Move action.
Addressing:
-Getting stuck with an extra movement point for nothing, or while trying to avoid that, unthematical/belief-suspending actions taken.
-Investigators with action-based traits being less useful than those with passive/triggered traits get brought up to level with the others.
Side effects:
-Somewhat Lessened difficulty = not for everyone.
-Carson Sinclair is more significantly changed than the others; not maintaining a 1:1 trade anymore.

Main problem: The ruling originally included Item actions, but that seemed to powerful. But when not taking item actions into account, this is an improvement to Investigators with action-based cards only.

Comments on improvements? I'm leaning on ditching this houserule.

Disclaimer: I am not a fan of house rules in general, for any game.

The problem with house rules is that they often are trying to address a "perceived" issue with the game, but all most of them end of doing is drastically affect the balance of the game in some manner.

In other words, house rules often change the game enough to cause far greater issues/impacts in other areas, than the area they are suppose to address to begin with.

Having said all of the above, if it allows you and your group of players to have a better/more enjoyable gaming experience, then go for it !

I thought maybe this, instead of item actions, possibly also instead of trait actions:
-You may resolve an explore token, as part of your move; consuming a move point while doing so. You may not move further ahead when prompted so by the exploration dialogue.

any2cards:
Generally, i'm with you, but mainly for another reason: It makes playing with different groups a bit of a hassle to set up common terms. Better then to stick with canonized rules.

MoM 2ed leaves little room for improvements. Most things run well rule-wise, i think. A very short list makes it somewhat clunky. Movement/Actions handling and balance is one, i think. The other is that the mythos phase sometimes can sometimes weigh down on the game tempo; but we've found it acceptable. The third is fire placement, but we sort-of fixed that with cardinal direction dice.

We've never felt the need to houserule X-wing or Arkham Horror.

When playing Zombicide, by comparison, we have a 2-page ruleset fixing (really, fixing) that game's probable lack of sufficient playtesting and broken/uncompletable scenarios. I probably won't buy a game from that company in any time forseeable.

Coming up with functioning house rules is definitely possible. Just like any segment of programmed code, though, it needs to be thoroughly tested before dismissed, alterered again, or finally, printed to be put as a note in your personal copy of the game. That can be tedious. Discussing the ideas in their unfinished state may help the process along a bit, which is the intention of the OP.

For two investigator games, I've been toying with a the following rule:

Step Ability - Once per round as a free action an investigator may move 1 space prior to taking an action. Normal movement restrictions apply. You may not extinguish fires when moving to a space using this ability. The step ability does not trigger character abilities (For example Rita's). In order to use this ability, the investigator must not perform a "move" action at any point during the round.

This rule works well to keep the flow of the game moving, and makes for fewer turns where a player feels unsatisfied with what they could do. This opens up a lot more opportunity to use investigator actions and basic exploration/trading. This does increase the action economy quite a bit for the players, so I have only tried it during two player games were the party is already struggling for actions.

Thanks for the idea! That's interesting -- for the most part, it's two player games that suffer the hardest regarding action economy. The fewer players/investigators, the less often you'll find viable occations interacting with them.

In that regard, it could be worth trying the following:
a) Wounded - For every action taken above one on that investigator's turn, that investigator must take one damage.

Instead of hard-capping the action economy; often effectively causing monopoly syndrome (you see that you'll loose the game with the highest probability, but there's x turns left before it will happen) in a 2 investigator game, this ruling would provide some agency over the situation, but with a fitting cost. It could perhaps be extended to any number of investigators (various participants in my shifting playgroups have expressed a diminishing interest to continue play when they're wounded, perhaps because of loss of said agency. Insanity is fine because however sometimes harsh, you're left with a choice). 2 investigator games should still benefit the most.
Alternates:
b)Adjust it to facedown damage if it proves too hard a bargain to be worth considering.
c)Another easing adjustment would be "turn a random damage card face up".
A midway between (a) and (b) would be:
d)"... must take one facedown damage. then turn one random damage face up."

EDIT: I just wanted to add that i only submit standard game sessions to the stats as to not skew them.