Modifying a heat stick to control heat?

I do partial boils on a weak electric stove; it used to take hours (literally) to get 2 1/2 gals to a boil. I bought a 'bucket heater' - basically a heat stick, but it was pretty weak & still took forever to get a good boil going.

So I built a heat stick using a 1500 watt water heater element.
It works great, gets 3+ gallons to a boil very fast, but...

When the wort gets boiling, it gets to such a vigorous boil that it 'spits' out of the kettle - all over the stove & floor. Even if I put the lid on the kettle it spits out the gaps caused by the heat stick protruding from the kettle.

If I unplug the heat stick the stove can't maintain a boil.

So - was wondering if there was some way to modify the heat stick & put in some kind of controller to dial the temp back a bit - ?? I'd like to maintain a boil but not so vigorous. I guess I could try building another heat stick with a lower wattage element as a last resort...

I appreciate any thoughts or ideas -
thanks
BT

How about letting the heat stick run and dial back total power via the stove controls? Perhaps I didn't understand you and maybe you are already killing the heat on the stove completely.

I've tried turning off the stove completely, The heat stick alone keeps it boiling VERY vigorously - so much that wort jumps out of the kettle;

The 'bucket heater' I tried is supposed to be 1000 watts & won't really bring 3 gallons to a rolling boil.

THe heat stick is 1500 watts & seems to be too much heat.
BT

What kind of electric stove do you have?
Is it the old school coils or glass top.
The old school stoves have spring terminals where the element slides in; if you could get similar terminals for your heat stick (long male spades may work) you could plug into these and use your stove controls.
If you do this you still need to be safe; there is a ground screw under the stove element that you will need hook your heat stick chassis ground to.

Or you will need to build (or buy) a PID or PWM controller; they range anywhere from $10-$40 and as a bonus you will get a crash course on electronics.
Several threads on this in the DIY section.

I have an old glass top stove, so I'll look into building a controller - thanks for the help!.

BT