I did a timing check, and found the timing to be at 10 degree BTDC. But when I accelarate, the timing retards all the way before advancing to 30 degrees BTDC. Is the timing reversing in this manner normal? This test was performed with the truck in park and reving up the engine. It consistently retards timing before advancing. So, I removed the SPOUT jumper and drove, to see if there is any difference. The vehicle exhibits no appreciable difference in power (the condition is that bad -- I still have to stand on the gas pedal). Once the timing has advanced, it sticks and does not return for about 3 seconds after releasing throttle; I thought it would return to 10 BTDC immediately; so that the engine can quickly rev. down. The RPM changes are sluggish both ways. Is the PIP (CID or CMP) sensor bad? Or is it the ignition module. Worse yet, is the distributor shaft slipping?