I have a 93 Econoline with the 5.0 motor, I just had new plugs, wires,cap and rotor put on it and now it is missing. Husband (in Iraq) thinks it might be the timing chain, since we were running it hot trying to get it home after it kept overheating. He wants the timing chain replaced asap thinking this could be the reason also he is afraid of it breaking and ruining the motor. Father (person who put in new parts) has no idea why it is missing, and says if timing chain does brake nothing will happen to the motor it just won't start. Now I have been trying to find stuff online about what would cause the miss and read that a vaccume leak could do it. I NEED HELP!!! Who's right who's wrong any ideas on what could be causing this? Thanks

 

Was it running OK before the new plugs, cap, rotor and wires? If so, it could be a bad plug, wire or the cap. It's not uncommon for new plugs or wiresto be bad. Also, check the new cap for any hairline cracks. This will also cause problems. Is the miss at idle or when driving? If it's noticable when idling, you can pull one plug wire off at a time andstartthe engine. This will cause the engine to stumble as in a misfire. Do this for each plug. The one causing the problem will show no change in engine runnability. Should be nothing wrong with the timing chain. Since the timing chain and gears are steel, its a WORK or NO-WORK senario like your father stated, so I wouldn't worry about a timing chain.

 

Everything was running fine until he put the new plugs in. The new cap was loose so he changed that but it didn't help anything. So he figured he would try new wires still didn't help anything, he took the plugs out and made sure they were gapped right and still no luck. I am going to try the one wire at a time thing that you mentioned. But to answer your question it misses both at idle and driving, however it doesn't do it until it warms up.