91 loyale problems

Hi,

Hard to guess just from that description, but I'd start with the simple things first:

Does the problem occur w/ all brands of gas? Sometimes the simplest fix is to change brand/grade of fuel.

A bottle of Techron or Berryman's B-12 in the gas tank helps clean injectors and remove gum and varnish from the entire system. Some would recommend taking this step first, before changing a fuel filter as mentioned below, to avoid clogging a new filter w/ old goo, especially if a car's sat idle for some time.

If you have SPFI (throttle body injection), a can of aerosol cleaner shot into the intake area can help.

--New fuel filter (Subaru OEM has worked and lasted better for me than aftermarket)

--Air filter

--Spark plugs (if you know how to read the plugs, you may see some clues. If not, many auto parts stores and repair manuals have a page showing common problems to help you)

--Timing

--Spark plug wires (if you have the specs, you can test w/ ohmmeter for resistance. Also, you can open the hood w/ engine running in the dark and look for arcing.

--Distributor cap and rotor (if you replace plug wires, I'd definitely let 'em have a new cap and rotor "just cuz!")

Moving up in complexity:

Check for any codes being stored by the ECU to see if any sensors are or have been problematic in the past and threw a code.

Disconnect each of the various underhood electrical connectors (engine off, battery ground strap disconnected), clean w/ aerosol cleaner (get the stuff for electronic/electrical equipment--better auto parts stores stock it), then reconnect using a bit of dielectric grease on the contacts in the connector (again, better auto parts store) to reduce future corrosion. (Do NOT use dielectric grease on the connector for the O2 sensor, though. I've seen articles stating certain O2 sensors can be damaged doing this.)

O2 sensor (if you don't mind splicing the feed wire, aftermarket is 1/4 to 1/3 the price of my dealer's OEM, and works as well for me.) Newer models will throw a code w/ a bad O2 sensor. My '90 Loyale doesn't, and I doubt your '91 will, either.

Fuel pump pressure low. You may need a pro to test that.

Oddball possibilities:

Incorrect t-stat temperature, "confuses" the ECU into thinking the engine's not warmed up, runs rich. Use Subaru OEM t-stat.

Timing belt incorrectly installed, with valve timing affected negatively.

Compression test if none of the above help: sick cylinder(s)? A skillful reader of a compression tester may also be able to diagnose a timing belt problem this way without having to unbutton the front of the engine--I personally can't.

Really oddball possibility:

If the car's an automatic, is the trans full of clean fluid and not slipping? If it's a stick, is the clutch disengaging fully and not slipping? Your post says "no responce" to additional pedal force, so I assume you mean the engine itself doesn't respond, as opposed to the engine responding and the car not moving faster? If that's the case, the trans/clutch suggestion's off the screen.

Good luck,

Rick