I just bought a 1990 rs auto with the 305. It idles rough when cold but improves when warmed up. Also it has a high end sputter at about 5000rpm or so. It sat for quite a while. I figure it needs the timing looked at and some good gas and maybe injector cleaner. Ideas? Thoughts?

 

Welcome, Jess
Congrats on the buy and Good luck
First, you may want to buy a Haynes manual for reference - always comes in handy.
The manual will tell you how to set base timing and base idle.
You may have to remove the IAC and clean the bejesus of the hole and the IAC.
Change fuel filter, remove existing fuel and add clean fuel and a can of Wynn's Injector Cleaner with a full tank of fuel.
You can also check timing chain slack by rolling up the timing marks and then roll backwards and if more than 10° of slack, replace timing set.

 

Assuming you don't have a service history record to show any recent ignition work, a tune up just may do it some good. When I bought my old 91 years ago, a new distributor cap, rotor, spark plugs and wires woke up the engine and cleared it of the stutter it had. I also rebuilt the TBI for good measure, which is easier than working on a carb. A "tune up" would be the first thing I'd tackle on it. When you have the cap off, look inside at the contacts, and at the rotor. If it's never been replaced, or was way long ago, the cause of the poor running engine might be obvious.

 

I had a similar problem with my 92 RS. I replaced the IAC, and cured the problem. I would still at least like 69 suggested, pull the distributor cap and have a look at the contacts and rotor. You may have more than one issue going on.

 

Having problems with my 94 Camaro. Sometimes it wants to sputter and other times it is fine. Any suggestions?? Thank you.