Mav3ry

Okay, so for the past couple of months i have been working on a 97+ swap comanche and i have ran into an issue with my 98 xj motor. The motor runs perfect, sounds and idles great gets oil pressure, but gas is somehow getting into the oil. When i let it sit and idle for around 20 minutes the dipstick level goes up around 1/4", and i have done this multiple times with the same result. I have checked the fuel pressure and it is at 47 psi and it holds the pressure overnight, i think it went down to like 25 or 30psi, so i know i don't have any injector leak down because if i did it should be at 0psi right?. I am running the xj fuel system aside from 6an lines from the regulator to the fuel rail and 19lb 4 hole injectors. I did a compression check and cylinders 2-6 have 120-130psi but cylinder 1 has about 90psi, this was also when the engine was cold when it was 10 degrees outside so id imagine numbers would be much better when warm. About a month back i noticed that cylinder 1 had the plug wire arcing on the heater core outlet so im sure that had some part in it losing compression since im not sure how long that had been going on, but i didnt notice any misses in the engine so not sure what was going on. My question is should 90psi really be enough to let this much gas in at a idle for 20 minutes or is there something that im missing. Any help would be greatly appreciated, Thanks.