1G Engine vibration after gapping spark plugs?

[ThatBerta]

So I have a 1990 Plymouth Laser RS Turbo 5 speed, I was reading that the spark plug gap should usually be set to around .028 - .032 and wanted to adjust the gap on my ngk plugs because i recently had my injectors bench tested and cleaned. It ran great after cleaning the injectors but it was still misfiring so I decided to check my plugs and decided to gap them since I haven’t yet since buying them about 4 months ago. They were pre gapped to around .036 so I just dropped them down to .030 but after doing so I’m now getting severe engine vibration revving from 1-2.7k rpm and again minor vibration from 3.5-4.5k rpm but then runs smooth after that. Does anyone have any idea what’s going on?

 

[jdxnc]

That would typically indicate it's misfiring on one of the cylinders.

 

[ThatBerta]

Yeah for some reason only cylinders 3&4 aren’t firing anymore. The wires are still getting spark on all 4 of them and they’re brand new plugs. Plus I just got my injectors cleaned and did the fuel filter about 6 months ago. It didn’t have this problem before I gapped the plugs. I even switched them around but the same cylinders were misfiring despite this. Any ideas on what it could be?

That would typically indicate it's misfiring on one of the cylinders

 

[pauleyman]

Yeah for some reason only cylinders 3&4 aren’t firing anymore. The wires are still getting spark on all 4 of them and they’re brand new plugs. Plus I just got my injectors cleaned and did the fuel filter about 6 months ago. It didn’t have this problem before I gapped the plugs. I even switched them around but the same cylinders were misfiring despite this. Any ideas on what it could be?

Yeah for some reason only cylinders 3&4 aren’t firing anymore. The wires are still getting spark on all 4 of them and they’re brand new plugs. Plus I just got my injectors cleaned and did the fuel filter about 6 months ago. It didn’t have this problem before I gapped the plugs. I even switched them around but the same cylinders were misfiring despite this. Any ideas on what it could be?

Verify the firing order. Also how old are the wires?