Cadillac Repair: 90 Deville Acceleration problems???, acceleration problems, pedel

Question
I have a 90 Deville that is acting strange. She doesn't want to accelerate right. When you apply pressure to the pedel it will gain a little speed and the start stumbling and trying to backfire. If you get off the pedel and let her rpms level off, you can accelerate again for a few seconds. Then suddenly she picks up and shoots off like a rocket. Almost feels like an overloading carb burning off the excess fuel. Did have EGR circuit fault code, changed it with no effects at all now I have a 39 code, also 49 and 49.  Have been working on this problem for 4 years 2 dealerships 6 mechanics and damn near every external part changed.  If you walked up and started her you would think it was the smoothest showroom smooth running 90 youve ever seen it still gets 26-30 on the highway (lots of popping thru the now open exhaust).I NEED SOME ADVICE. New timing chain in the past weekk or so and have had the timing checked again sincce then.

Answer
Code E30 = RPM error to great.

Code E49 = Air management system fault.

why do you have 49 listed TWICE ?.


You will need simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.