"Extended" visa runs

I have a hypothetical situation.  I'm a US citizen, married, and we go to Malaysia.  Our passports allow us to stay visa free for 90 days.  We love it there, and want to come back to Malaysia as often as possible, but we don't want to do anything illegal.  If we stay for a week in Singapore, then return, I know we can probably go back to Malaysia once more in a year, but staying elsewhere for only a week could cause problems.  Our passports allow us a to stay visa free for 30 days in either Indonesia or Thailand.  If we did THAT, would there be an issue with Malaysian customs?  Stay 90 days in Malaysia, 30 days in Indonesia, 90 days in Malaysia, 30 days in Thailand, 90 days in Malaysia, and so on?  Anyone know?  Could I just ask Malaysia's customs and immigration ministry instead?  I'd appreciate any thoughts on the matter.  Thanks in advance.
What i know is, Malaysian customs usually don't like visa runs but for returning 2nd time with a break of 2 weeks there is no problem at all

The best visa run in SEA IMO is Vietnam
My mother in law had come to stay with us pre covid19. I got her a one year visa issued in Dubai by the Malaysia Embassy, however, Immigration Malaysia when she landed allowed her to stay only a month. She had to do a trip out and back, so would travel to Thailand of 2 nights and return. She had no trouble at immigration coming back, but they would not allow her continue staying here longer than a month as that's what her passport entitled her although she had a one year valid visa.

Hope this helps.
I wouldn't ask Malaysian immigration. They will simply say no...even though the decision on this is actually not a specific policy. It's up to the discretion of the immigration officer on duty and based on their judgement if they think you are actually practicing tourism rather than working or involved in other activities that require another visa (establishing a domicile...in lieu of getting an MM2H).

Obviously every nationality is allowed different terms of stay. Most countries are allowed 90-days, but some are allowed only 30-days. And some require an actual visa prior to the entry. The USA gets a 90-Day visa.

Some suggestions...don't stay until the very last day of your tourist pass. Leave a week or a few days early.
Stay more than a week outside. Some people will do a quick turnabout, but that indicates you my not be an actual tourist. A month should be fine.

I've heard that only two entries a year are allowed, but others seem to to make three or even four visits. I think this depends on the officer whether they allow entry or even reduce the term of the visa to a month or ten days. I'd consider putting an additional country in between the "period out" (e.g. My>Thailand>Singapore>My or My> Indonesia> Singapore>My).  That looks more like a "tour".
After a couple of visa runs you may get a stamp in your passport, that you have to report to Immigration within a week. Should this happen, you could consider traveling to Bangkok and have your passport replaced by the embassy there. Not sure how long it takes for US replacement passports overseas, but it gives you the benefit of having all empty pages, next time you arrive in Malaysia.
After a couple of visa runs you may get a stamp in your passport, that you have to report to Immigration within a week. Should this happen, you could consider traveling to Bangkok and have your passport replaced by the embassy there. Not sure how long it takes for US replacement passports overseas, but it gives you the benefit of having all empty pages, next time you arrive in Malaysia.
- @micern

I dont understand your comment since ins and outs are a matter of computer record. They see your record on a screen right at the checkpoint. If a person shows with a new mid-trip passport they will see that and want to know why -- and it wont have the desired effect either.
@therichardjohnston1971

Visa runs are dead and have been for a long time. A person could get away with one extended run, maybe. There is no official published rule, youre at the mercy of a checkpoint clerk. This doesnt mean youd be denied entry (though in theory it could happen), it means you'll get a stamp in your passport to report to your local immigration office where you will be put in front of a manager who will likely tell you to pack up and leave Malaysia within some amount of days. There is no law code to quote here, its a matter of everyones experience over time. Thailand is the same, I think worse, which means that trying to repeat trips to Thailand to relieve pressure on the Malaysian problem will be met with the same resistance. Talk about a rock and a hard place!

That said, during the pandemic the official rule is that those who are allowed to enter have to have a visa -- student, work or marriage --general tourism isnt open unless someone has new news. See this for entry guidelines,  https://myentry.myxpats.com.my/app/   but its almost two years old so Im not sure whats changed, if anything. Often, changes or updates are made by comments-in-passing by some minister and not on websites. I think Malaysia has let go of the Travel Pass and quarantine. Actually, im finding that airline booking sites have latest info, better than what govts publish. Its a very confusing time for entry and entry/exit/entry due to Covid restrictions.