Toyota: 93 toy p/u, fuel injector cleaner, fuel stabilizer

Question
my pick up is a 93 4cyl, auto, 2wd, and 64000 miles.  The other day, it started in park idleing up and down, now sitting at a stoplight it does it in drive.  I also notice that my gas milage has gotton bad.  I did a tune up about 4 months ago.  Any suggestions about the idleing?

Answer
Did you do a full tuneup?  The couple of things I'd check are: PCV valve and IAC (Idle Air Control).  You can also check your EGR and see if its clogged or dirty.  I'm tryin' to think of what 4 cyl is under your hood to give you a better idea and to tell exactly where they are at.  If you do find out, you can write back and I'll give you more detailed info. Clogged fuel filter will also cause that.  As far as ignition..  Maybe the rotor arm and distributor cap if either one is not replaced.  

Finally, using a fuel injector cleaner wouldn't hurt.  I recommend "Sea Foam".  It's a bottle that does wonders for engines.  Its an injector cleaner, fuel stabilizer, and crankcase cleaner all in one.  You can actually use the ONE bottle on three different places of your car!  It's about.. (Around here, Maryland) 5.88 a bottle.  Check it out! I hope this helps and sorry for being long-winded!