Particles always cause gravity and as you point out, it really is due to the energy spinning within. Inertia, gravity, and magnetism are all aberrant effects of that inner motion. But now how do you propose to support the notion that a static charge field (no particle participation) will cause a gravity field?
Well, this is where pictures would really help.
A photon, for example, has a spin in one plane only, thus allowing free flight along its axle (no forward inertia). But now imagine that you are standing as an extremely small being exactly beside that spinning beast. You would have to sense the effect of a positive wave or peak of EM passing near and then very quickly reversing as the spin led the negative wave near. If you had any charge to you at all, you would no doubt be shaken to bits at the speed of light vibrating and rattling your brains in a gamma frequency.
But now, if you step back just a bit, the sense of the effect lessens of course. Necessarily what you feel in your new position will be slightly delayed from the true position of the waves within the spinning photon. There will be a phase shift. The further out you go, the more shift there will be.
The prior traveling wave (and thus energy) concerns led to the belief that the effect of what you would feel from that spinning could not exist at all else energy would be leaving the photon. But that is where the error was. The wave you would feel does not represent an energy propagation (for more technical reasons). The vibrations that you would feel radiating from the photon (or any particle) will be reversing at the rate of the spin which is at the speed of light in a very tight loop causing a gamma range frequency (detected back in the 60’s). But also they are emerging from the particle at the same speed of light (necessarily exactly identical). What that means is the phase shifting that you sense will be exactly 45 degrees with respect to the distance away from the particle you move.
Visually, if you plot the wave fronts, what you would see is a 45 degree spiral wave pattern centered on the particle.
Now, forgiving the confusion that I haven’t explained yet concerning the energy question, think about the facts that every particle (and every formed mass) is made of that same spinning EMW and every particle is causing that same spiral wave front around it. What happens to the particles as they experience the wave fronts of each other?
Close examination will show that there is an impedance effect that slows the EMW peak within that is closer to the other particle. But there will be less effect on the opposite side (very much like your own explanation). That causes roll and positional shift much like a bicycle tire just beginning to touch the ground as it spins.
The interesting thing is that the wave fronts are at exactly 45 degrees because due to that, the roll and positional shift will be exactly straight toward the other particle - exactly.
It doesn’t matter in which direction the spin might be occurring at any one moment. The spins will shift and compensate due to impedances and always align themselves such as to cause the same positional influenced shift. It doesn’t matter how many different directions the waves are coming from, the particles spin immediately compensates (nothing to prevent it) such as to head the particle toward the averaged field direction, the “center of mass”.
This compensating spin must necessarily take place simply because there is nothing to prevent the EM spin from adjusting to the variance in impedance. Gravity MUST take place, because you cannot stop their spin nor control the direction of their spin while they are under the influence of each other. And trying to reverse the effect is logically impossible. The best you could accomplish would be to magically remove the effect, but there is no reversing of it.
As to the energy question. That is a longer and deeper story and is why metaphysics must be understood before physicists go off wild in their imaginings of “strangeness, bottemness, topness, charm, flavor, colour, strong, weak”, and whatever forces and properties.