First time user of this site. 1994 GMC Z71, 350, TBI. 182K miles. Completely stock. Have had this truck since 1995 and has always run great. Plugs wires, cap and rotor are ~2 years old. Lately I've noticed a stumble under load, the tach also has a slight jump to it. It has gotten worse and now pretty much misses all of the time, worse after it warms up. At times it seems to almost clear up for a few miles but the miss will return. I checked the basics (plugs, wires, cap, rotor) Wire and plugs look great. I ended up replacing the cap and rotor and changed the fuel filter. No help. Coil was original so swapped that out, the tach is steady now but still misses. No light show under the hood. I read somewhere that the pick up coil or ignition module can break down over time. Given the age, I went ahead and installed a new distributer, set it for zero with the wire under the glove box disconnected. No help. I did a vacuum check and it pulls a steady 20 in. Checked fuel pressure and it was 12 lbs. No check engine light, codes have not been scanned for. What’s left? fuel injectors? I read somewhere to shine a timing light at the injector spray to see the spray pattern better. It looks cone shaped and isn't “dumping fuel”. It was during the spray check that I noticed that some of the time, when the engine misses, the timing light will not flash. Not always, but sometimes. I imagine the other times it's missing on another cylinder. Is the corresponding timing light miss mean I'm still chasing an ignition problem or can it still be fuel related? Sorry for the long post, wanted to get as much info as possible. Thanks in advance for any advice.