You just tuned up your 1994 Chevrolet Silverado and afterwards your truck is running very rough bogged down and the service engine soon light is coming on could i have any vacuum leaks if so where?
Not sure of what your tune-up consisted of.........but an obvious one would be if you got spark plugs wires mixed up, but lets assume you didn't, did you gap the plugs before you installed?. Did you make sure every spark plug boot snapped down onto the plug? I use spark plug jelly or lubricant to make the boots slide over the plug and it keeps the boots from seizing. Get a spray bottle and spray water on yoru exhaust manifold and try to determine which cylindre is not firing and look at that one. If the water evaporates quickly or steams then go to the next one. You are lookign for the cool cylinder, the one where the water takes longest to evaporate. If you want to fidn vacuum leaks, I suggest you get a can of throttle body cleaner and whiel the engine is idling, spary a short stream at the end of each vacuum hose. If the engines picks up revs, you have a vacuum leak so fix that one and then continue on doing each connection as you go. The vacuum of the engine will suck the throttle body into the engien and it is like adding some fuel to the engine, thus when it revs, the engine is not pulling vacuum but pulling in air and too much air and ot enough gas will make you truck stumble and run too lean. If you have to repost, make note of what your tune up consisted of so we can better tell you other areas you may need to look at.