sputtering at half throttle
 

Hi, I have a 1986 D21 with the Z24 EFI 2.4L engine, (150,000 miles). It is sputtering and puffing out black smoke if I push the throttle past half way. This truck runs like a Swiss watch otherwise. Anybody else have this issue that can help me. I have been reading on the net, seems like it could be a bad coil, TPS? Thanks in advance....Gary