MAP sensors used to be a high-failure item and they often caused the symptoms you described when they had just started to fail but weren't bad enough to trigger a fault code. I'm not a fan of replacing random parts but you might want to try a new one or pick up a used one from a salvage yard. Don't overlook a vacuum leak since MAP sensors measure intake manifold vacuum.
You didn't say which engine you have. If you have a single camshaft four-cylinder engine, the dowel pin between the cam and sprocket can shear off and the sprocket can turn a little. When the camshaft is late by the equivalent of one tooth, the Check Engine light will turn on and there will be a fault code "cam and crank sync". At two teeth, the Engine Computer will shut the engine down to protect the valves. Before it gets to one tooth, the engine will not have the proper response but there may be no fault code set.
The TPS might cause a little hesitation but that's all. A momentary glitch in the signal voltage will be detected by the Engine Computer which will set a related fault code. Even with a hard failure and a fault code, it won't cause what you described.
I don't think fuel pressure is the cause either. Some GM engines won't run when fuel pressure is down just a few pounds, but my '88 Grand Caravan runs 50 pounds of pressure and it will still run fine as low as 20 pounds. I drove with a fuel pressure gauge attached to the radio antenna for over a year while chasing an intermittent problem. That's how I learned how it runs with the wrong pressure. GM also had a huge problem with leaking pressure regulators but I've only read about that on a Chrysler product once. I've never heard of one having low fuel pressure caused by the regulator.
You may need to connect a scanner to view live data to see what the Engine Computer is seeing and reacting to. When there's no fault codes and the cause of a running problem isn't obvious or easy to diagnose, a visit to an engine performance specialist can be less costly and faster than trying various things.
Thursday, October 10th, 2013 AT 11:22 PM