Okay car is a 88 camaro with a 350 Tbi. A few weeks ago I went on a pretty long road trip (bout 350miles) when I came home the next day and drove the car to work it started stumbling really bad around 35-40mph. I changed my dist.cap and checked all my plugs/wires. I finally decided to throw a light on it to check the timing. It's a little advanced maybe 4-5degrees. Could that be my problem? And how could the timing advance its self like that?

 

First Guess: Timing has NOTHING to do with your stumble.

Second Guess: You forgot to disconnect the wire that returns the engine to base timing instead of computer-controlled advanced timing.

 

I disconnected the est before I put the light on it. I'm going to set it back to 0 in the morning and see if it helps. If its not the timing what could it be? The injectors look okay the plugs and wires are good and my pick up coil looks okay.

 

Check fuel pressure?