With all the rain we've had the past 2 days my truck isn't idling right. It's a 91 with a 302 and e4od. It doesn't die but the idle bounces from 1000 rpm to around 400. But when I get going it drives fine but once back at idle it bounces around a lot. Any ideas?

 

And now it keeps shifting in and out of overdrive. If anyone knows what it might be can you please help me? This is my back up vehicle my main is down too