that sounds more like a bad converter or the timing is of way bad in it,what it does is when the timing chain and gears get real worn out in them it causes the timing to be so far off that it robs them of power,first check the converter on it,because a stopped up converter is a very common cause of that happening,the low compression will cause a slight roughness on running it,but not cause what yours is doing,it should smooth out at higher rpm,s,id suspect bad timing or the converter being the cause of that,if its above 125 thousand miles more than likely the chain and gears are worn in it,good luck.