I know this has been on here a while but I would like to bump this thread and inform everyone what I have done lately. I replaced the head gasket because it was blown foward of #1 cylinder. once I got it back together the valves were all out of adjustment so I bought the shims and got them all back into the correct adjustment. I also changed an injector that was bad. Started up again and it ran better than it has since I owned it. Keep in mind it never really ran that great. Slowly I started losing power again. The timing still jumps about 5 degrees everytime the light hits. It idles fine and does not miss or back fire. Revs up okay but it just seems like something is holding it back. Pleas help!
also the TPS is new and adjusted correctly.

 

does your runner have a camshaft or crankshaft position sensor

 

camshaft

 

I'd replace that and see if that helps

 

When I replaced the head gasket, I went through,the heads and checked everything. I mesured all the lobes of the camshaft with a micrometer, put in new valve seals, and used a straight edge to make sure the heads were not worped. Everything was in specs. I'm leaning towards the distributor, but I also think it could be a fuel issue. I just have never had timing issues like this. Anymore input would be appreciated.