hi there, i need some help, this truck has this problem, at first looks like a simple misfire but all the ignition parts are new, the compression is even in all 4 cyls 150psi, i replace the distribitor complete, and nothing, now if i disconnect the maf sensor it runs great, no more roughnees, and i replace the maf sensor with a oem one and still the same thing, i already check the wiring harness, and continiuty,and is in order, also the fuel pressure and regulator were check ok, please if someone can help me let me know. thanks

check the vacumn..

also check the valve b4 the egr for proper function...