I have a 1990 Toyota Celica GT with auto transmission. Lately I've been having problems with it stumbling when accelerating. It's starting to become real annoying. It would happen occasionally when it was cold outside but once it warmed up - no problems. Now it's starting to happen all the time. It only seems to be a problem when I accelerate, not when I'm in neutral and step on the throttle. When the car idles its quite steady and runs smooth but when it's in gear and I gas it (whether fast or slow) it starts to stumble. I thought it could be related to the fuel pump or a misfiring plug maybe even transmission. Any insight would be greatly appreciated. Thanks and Happy New Year, Darren.