My camaro is a 1991 rs with a 3.1 liter engine. Two weeks ago it started running really rough. When i tried to maintain a steady speed it would shudder violently. Then it would not accelerate past 55 then 45 then lower still. After a week in the shop they gave it back and it will not idle when in drive or reverse. usually the car just dies unless i apply the gas. when coming to a stoplight i press the brakes and the car stalls out. I've replaced the MAP sensors, the 02 sensor, the coolant temp sensor, the ECM, the fuel pump relay, the fuel pressure relay, the vacuum container, 90 percent of the vacuum tubes, the IAC valve, the fan relay, 3 busted fuel injectors, cleaned out the EGR, new distributor (cap and rotor also), and a few other things the shop put in for me. The tach is broken but I can tell that the idle starts acting up at a stop. First the car shudders then dies. There is one more hose on the back of the engine block i need to replace but I'd like to know if there may be something else causing the problem. The engine seems to be getting plenty of fuel, most of the gauges (including temp and oil pressure) are functioning and reading well. If you know of anything else to try or have fixed similar problems, please let me know what you did to fix it.

 

If that hose is for something from vacuum, it can be torn. I would listen to the car and see if you hear a hissing noise. Sounds like you are running lean. Vacuum leak would be a good place to start.

 

Best of luck on that one, I never did discover why my old 305 was doing the exact same thing yours is doing except the highway stuff. There's a spray you can buy that you can use near the vacuum lines that will make the motor rev up where there are leaks, but the name of the stuff slips my mind.

As you've said, you've changed 90% of the vac lines, maybe the other 10% is the problem hehe!

You've also changed the ECM, which also helped on mine for a while but the problem seemed to return.

Hope you find it!

 

Well, I'm at my dorm right now and my car is parked in my parents' garage. Obviously I need to replace that one vacuum line which doesn't look torn or anything and was unresponsive to ether. (Forgot to mention that the mechanic I gave the camaro to tried to find a leak with ether)

THere is no hissing noise unless I take off the air cleaner. I did put a TPI dual snorkel intake on it and haven't routed the air temp sensor to it, but i left in the old air box with the sensor and never had problems with that. still, i know that the car is running lean but if I use premium gas then there is no indication of a problem. (the spark plugs get dirty in a hurry, but nothing else seems to be acting up)

I've read a lot of posts on similar sites about this problem... It seems like everyone ditches their car when it starts this... But I'm in college with a crappy job that gives no hours so i can't exactly get a replacement right now...

 

A lot of people on a ton of sites have the exact problem i listed above so i was doing some research and found a site ( http://autotechrepair.suite101.com/article.cfm/050106) That sheds some light on possible problems. The Dexcool antifreeze eats away the intake manifold gaskets causing them to leak. in some cases as soon as in 2 years. there are special locking bolts you can get to help stop the process. the problem is common in chevy 3.1 liter engines and chevy 3.4 liter engines. definitiley on my list of stuff to try soon.