I am the devoted owner of a 1990 Subaru Legacy Wagon w/about 250K miles.
A couple months ago my wife came home complaining that our 90 Legacy was running rough. I checked the plugs which seemed a bit fouled and I had some plugs in the garage, so I changed them out and voila the car was back to normal.
The car has been running great until about two days ago after I’d gotten some gas. About 5 miles later it started running like it was missing. It also develops a bad shake at about 45mph that goes away if you let off of accelerator. In park other then a bit of a rough sound at about 2k it revs just fine, it is only when the car is driving that it feels as if it is missing.
Thinking it was spark related, I pulled the plugs, shined up the contact points and put new wires on. Then to make sure there wasn’t a fuel issue I put in some fuel line antifreeze and changed the fuel filter.
I drove it about 15 miles and there is no change. HELP
Still using points? I would replace them,they are cheap,need to be eliminated as a possible source of your concern.Why did you not do them when you did the plugs?Do you have a dwell meter.You could benifit from a engine “scope” I havent used or seen one used in a long time.
I think he means he cleaned the contact points where the distributor rotor connects to the cap. I doubt you could “retro”-fit a set of points on a 90 subaru even if you wanted to.
To the OP: Be a big spender and do a full tune-up. NEW plugs, wires, distributor cap and rotor. Running some fuel-injector cleaner might not be a bad idea either. This is just maintenance that needs to be done anyways, and if that doesn’t clear it up we can start looking for problems. Also, if you have a compression tester, you might as well do a compression test while you’ve got the plugs out.
I suspect the fuel pump may be weak and you may have to replace the pump. Check the fuel pressure and see how that is. Another possibility is a dirty throttle position sensor.