91 Regal won't start. PLZ HELP!!!!!

I have a 91 buick regal custom with the 3800 motor. I got it from a buddy of mine who said the last time it ran, he started it up and went back into the house to get something and when he came back out the car had shut off. A shady tree mechanic told him it was the timing belt or chain...not sure which one this motor has... I've tried many times to get it to run. It acts like it's going to start then doesn't. It will backfire sometimes and then sometimes it coughs back out the air intake. I've cleaned the injectors and cleaned the plugs. It's getting way to much gas that I can tell because when I pulled the plugs out again they are wet from gas. The only code that I was getting was a code 33...and that pointed to the MAF sensor so I replaced that and that cleared the code but still the motor will not start. That was the only code I got. This is the L series so it doesn't have a MAP sensor on it. I had the module under the coils checked and it's good also... I have plenty of spark too. checked all the fuses.Please help and Thanks

It'll be a timing chain, not belt.

How did you check for spark? One good backyard way to check is by pulling a sparkplug, plug it into the plug wire, and rest the sparkplug threads on something metal. The metal piece you place it on has to be clean with minimal paint. Then have a buddy try to start it and watch the plug for spark.

Generally best to do this in low-light situations but many times you can hear it.

It has a timing chain, and when they get worn enough to slip a tooth or two, they act just like you describe. Sometimes you can even get them to start, but they have no power and barely run. A quick check is to hook up a timing light and watch when the spark occurs while you crank it. If it is after top dead center, the chain has slipped.