Scotty, I have a 1988 Lincoln Town Car with 114,000 miles on it and not a spot of rust. Over the weekend I gave it a tune up, spark plugs, new wires, new distributor cap and rotor, and even changed the fuel filter, all with new Motorcraft parts, now the car is running rough in idle and shakes when driving. I made sure to put the wires back exactly in the spot they were supposed to one at a time. What do you think could be happening? It didn't do this before the tune up. Thank you for the help!
I'm still gonna bet on spark plug wires switched.
Either that or you damage a plug wire and you have a misfire. When idling see if you get a puffing sound out the exhaust pipe. Should be even flow, no puffing.
Yes, I do recall hearing a puffing type sound coming from the exhaust after the tune up. I'm going to double check the wires later today and find a firing order diagram for the engine to make sure it's correct. One of the wires did seem like it was a little looser than the others.
Go back over each thing you did one at a time. You'll probably find your mistake.
I have also bought brand new spark plugs only to find that some of them have no conductivity thru the plug. I now check them all with an ohmmeter before installing them.
Did you gap your plugs? Some plug boxes claim the plugs don't need gapped out of the box, but old cars are a lot less tolerant of varying plug gaps than new ones. They don't have computerized coils producing spark that can easily compensate for slightly off plug gaps. A new wire could be damaged internally and not carrying spark properly, which will make a cylinder not fire properly. It won't stall a V8 like a 4-banger but it will run poorly. You can test this with a multimeter by measuring the resistance in the old vs new wires.
Also, was your cap and rotor also OEM Motorcraft? The ignition system in old cars is very simple. Pretty much every problem is something mechanical or there's a really basic electrical issue. If you still have the old cap and rotor assembly, swap that back on and see if it does the same thing. If it doesn't, your new cap and rotor is defective.
I ended up buying a OBD 1 scanner and hooked it up to the car. Turns out that the timing on the distributor was off and there's a vacuum leak. This is my first older car so if you happen to have any advice for adjusting one of those, it would be awesome!
You will need a device called a timing light to set your distributor's timing. There should be a label under the hood on the fan shroud that tells you the proper ignition timing, among other things. On my Pontiac 301, it's 10 degrees BTDC (Before Top Dead Center). I haven't used one myself, but there are several people on here who probably have. Ask in a new topic.
The vacuum leak should be relatively easy to find, but there's probably more than one. Spray around the engine with carb cleaner or starter fluid when it's running, but try to do it when the engine isn't hot to reduce fire risk. The engine will slow down when you hit a leak. Replace all of your vacuum hoses for good measure, they tend to be where leaks start. Do them one at a time. You may have emissions devices on the lines, so spray them and listen for RPM changes. If you don't live in an area where they do emissions checks, disconnect the stuff if it leaks and plug lines. My Catalina's EFE valve is broken, I can't find a replacement and it has a vacuum leak so I capped that line.
Update. I have checked the firing order and I have correctly wired everything up. None of the wires are damaged so I'm not sure what it could be