Pull the VIC out and check the connector. It's notorious for lose contacts there. There are 2 things you can do:
1) when you pull it out and disconnect the cable, you'll see the connecter has 2 rows of pins, like this ::::::::
You can GENTLY bend the pins towards the centre, in sense that you bind the top row towards the bottom and bottom row towards the top. GENTY, with a small flat-head screwdriver. That way they'll make better contact to the cable connector. That did it for me, never had the intermittent problem since.
2) if it's not the cable connector, it's the soldering joints of the connector pins to the PCB board itself, within the VIC. This fix would require you to pull VIC apart (easy, it's held together with plastic tabs) and to check the soldering joints, because some of them are most probably cracked. Resoldering them will fix the problem. Some resolder all joints, some just the cracked ones - it's up to you.
Beauty is in the eye of the beer holder
* 1994 ZJ (by VIN) with a 1995 engine (PO knows why)