RB Eater is right-
Get new fuel injectors. My shop had good ones laying around they sold for $75 each, or get new aftermarket ones. (But I've got no experience with aftermarket)

Then, have your idle set/tune up by someone who knows what they are doing.
Now the car should run right.

What does "blown exhaust" mean?
-cause it may be the next to do, or not-

Evil Aviator's advice for shocks/springs is correct, make sure to check the for sale section first-

You will never get over losing your RX7 if you sell it. I missed my first one for 9 years until i bought two more.

steve

 

Sounds like a bad idle valve or one of your injectors is bad?

Go through, pull your injectors, get them cleaned, serviced, and flowtested.

If you live in a non-emissions state, I highly suggest installing a blockoff plate kit while everything is apart. Also, swap to a dual-belt alternator pulley.

But definitely tune up the suspension. At the first least, new balljoints, and tierods. More extreme, new shocks + coils. While the rear suspension is apart, you can install some DTSS eliminators to get a more positive feel in the rear.

Yeah. Stuff like that.

-Richard-

 

Yes have injectors cleaned, I'd pull the lower intake off also and replace all vacuum hoses. I pulled my uim and lim to clean my sticking aux port valves and pulled the throttle body off and cleaned the back side. my 88 vert na runs great idles better and picked up 1 mpg. I got the racing beat cat back and bonez silencer/cat waiting to install them next week, the exhaust cost 1k thou after shipping. good luck

 

I 2nd, 3rd or 4th what people have said. Fix it first. It does sound like an injector problem so get them cleaned or look for new ones for a good deal. But consider a tune-up, check plugs, wires, air filter, fuel filter etc.

After you fix the 10 mpg problem, then fix your exhaust. Racing Beat is tested and true, but a cat-back is 600. A few years ago I picked up an NA with custom exhaust with magnaflows on it and I have to say it sounds great and your average muffler from them is around 100 bucks, combine that with a presilencer, in my case it has a turbo presilencer and you have a nice budget exhaust.

For suspension, I put KYB AGX Shocks and racing beat springs. Could not be happier. Then I gave the car to my bro. He still drives it and loves it.

Something to consider.

 

I've been thinking-
You mentioned the injectors were cleaned/tested recently-
It could be the Fuel Pressure Regulator, one of mine had similar problems as it got clogged up over time.
I'd still replace the injectors in any case.
steve