Laminator_X
Once & Future KMC Hawkeye
IMP does not make and has never made any sense. If the Flash is mass-dilated to such an extreme level, he should be time-dilated just as extremely.
Problem 1: He would never connect with his opponent because the opponent would be moving much faster in time than the Flash. The Flash would only see where the target had been long before.
Problem 2: As the Earth itself would also be moving through time much faster than the Flash, he runs the risk of either being smashed by collision with the planet itself, possibly causing an environmental cataclysm, or being left flailing his feet madly in empty space as hours pass for the planet in mere seconds for the Flash.
I know it's a comic and science shouldn't be considered so strictly, but they kind of take you down that road when they try to have it both ways with stuff like the IMP. It forces you to think about the science rather than simply hand-waving any inconsistancies.
Don't really think of is as being struck by a near infinite-mass travelling at near-light speeds, as it really can't be that. It's a force bolt with extremely short range (touch) that he has to run really fast to charge up; nothing more, nothing less.