guys,
i have a 1990 k1500 4x4 with 5.7 and automatic trans.
it has 161k miles.

recently i have been experiancing intermittant pinging. usually happens when it is warmed up and mostly on acceleration between 1-2 shifts. its really strange, because it will do it once, then wont do it at all the rest of the day, and might not happen again for days. the pinging sound is like if the timing was off.
6 months ago, at 154k miles, i did a complete tune up, plugs, wires, rotor, car, pcv valve, and also egr valve and solenoid, idle air control valve, throttle position sensor, and the knock sensor.
at that time i also checked the timing, with removing the connector up on the firewall( i forget what its called, but followed the directions in the manual), and all has been well up til now.
a month after the tune up i had to replace the starter and solenoid, and at that time i noticed the connector for the wire on the knock sensor was kind of broken. pushed it on as well as i could. today i check it and its still on, but im still not thrilled about how it fits.

so, should i get a new connector for the wire on the knock sensor ?
do you guys have any other ideas where i might start to look ?
it is not showing any error codes on the check engine light.

any help would be greatly appreciated, thanks