Volvo: 1988 Volvo, scan tool, wire harness

Question
Trying to find the plug to run diagnostics on it and what number of plug?  Car in the morning runs pretty good, but in the afternoon it barely run, then takes off and drives normal until you stop at a light, then it barely goes again.  Do you know what might be causing this?

Answer
Kerry,
There is not any diagnostics on your vehicle. The dealer has a scan tool they can hook up between the control unit and wiring harness run the car and compare the reading they have against know good readings.
Things you can test are the pre pump, try a know good MAF, make sure the wire harness is not frayed and shorting out, make sure the fuel pressure is correct.