Pontiac Repair: High, irregular Idling, last ditch effort, pontiac firebird

Question
I own a second hand 96 Pontiac Firebird, with a V6 engine. It has an engine allegedly from a 98 Firebird with 60,000 miles on it. I had been noticing a ticking sound when accelerating, and irregular idles, sometimes around 1500 rpm, which concerned me so i took it to a service station and they told me it was to do with the EGR valve. Eventually it transpired that it was a tube to the EGR valve that was 'bad' and needed to be replaced, costing me $162 inc Labour (please please tell me if i was charged too much..). Since then, the ticking has gone, however, the irregular idling remains, and i fear may be worse. Do you have any ideas as to what this maybe?? Its worth noting that the 'service engine soon' light came back on the very next day after i got the car back from the service station. What do you think may be causing this, and what do you think i should do? Thankyou for any help you can offer me, i'm at the end of my rope with this car and have lost pretty much all trust in the people i have taken it to. Many thanks, tom

Answer
Hi Tom:

Well an Egr problem can cause an Idle issue Especially if the valve were sticking open. That would give the engine a Vacuum leak and a fuel injected engine with a vacuum leak is like steping on the gas pedal the idle will increase. You could have a nother vacuum leak causing the problem as well. I take it that more than likely has a 3800 V6 not the 3400??? The 3800 engine is the better engine in these cars and they rarely have idle issues unless something is realy a miss like a vacuum leak or a incorrect PCV valve something along those lines. what ever the service engine soon light issue is may or may not be the cause of the problem. The light may be on due to another problem or the problem is the cause of the light and the idle issue as well. I would try a different repair shop ask around peopl that you work with if they have a reputable shop they take there car to. Last ditch effort take it to the dealer and explain you history with this car and expalin you on limited funds and if they can cut you a deal on the diagnosis time if you get it fixed there.. It may be something really simple or not.. with out seeing it it's hard to say what the issue is.. What was the code that was causing the light to come on before??? Good luck :}