Check engine light

The engine computer has detected a problem, set a diagnostic fault code, and since the problem could potentially adversely affect emissions, it turned the check engine light on. The first step is to read and record the fault code number. The people at many auto parts stores will do that for you for free, but most can only read codes on the newer OBD2, (on-board diagnostics, version 2) emissions system that became standard with '96 models.

You can read the codes yourself by counting the flashes of the check engine light. Go to this page for the instructions:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

You can get an idea of the severity of the problem by how the check engine light acts. For intermittent problems like you have, with less-serious problems, the light will turn off while you are driving and the problem stops acting up. If it is a little more serious, the light will "latch" on, and even if the problem stops acting up, the light will stay on until you turn the ignition switch off, and restart the engine. If it is still more serious, the light will be on any time you run the engine, even when the problem is not occurring. The most serious problems are when the light is flashing. That means too much raw fuel is going into the exhaust system where it will burn in the catalytic converter, and overheat and destroy it. You are supposed to stop the engine right away to prevent that. That flashing light only applies to the 1996 and newer models.

Have you read the fault codes?

You can do it yourself. Only Chrysler makes it easier than this:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method